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Gao W, Zhi G, Zhou M, Niu T. Growth of Single Crystalline 2D Materials beyond Graphene on Non-metallic Substrates. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2311317. [PMID: 38712469 DOI: 10.1002/smll.202311317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 03/14/2024] [Indexed: 05/08/2024]
Abstract
The advent of 2D materials has ushered in the exploration of their synthesis, characterization and application. While plenty of 2D materials have been synthesized on various metallic substrates, interfacial interaction significantly affects their intrinsic electronic properties. Additionally, the complex transfer process presents further challenges. In this context, experimental efforts are devoted to the direct growth on technologically important semiconductor/insulator substrates. This review aims to uncover the effects of substrate on the growth of 2D materials. The focus is on non-metallic substrate used for epitaxial growth and how this highlights the necessity for phase engineering and advanced characterization at atomic scale. Special attention is paid to monoelemental 2D structures with topological properties. The conclusion is drawn through a discussion of the requirements for integrating 2D materials with current semiconductor-based technology and the unique properties of heterostructures based on 2D materials. Overall, this review describes how 2D materials can be fabricated directly on non-metallic substrates and the exploration of growth mechanism at atomic scale.
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Affiliation(s)
- Wenjin Gao
- Tianmushan Laboratory, Hangzhou, 310023, China
- Hangzhou International Innovation Institute, Beihang University, Hangzhou, 311115, China
- School of Physics, Beihang University, Beijing, 100191, China
| | | | - Miao Zhou
- Tianmushan Laboratory, Hangzhou, 310023, China
- Hangzhou International Innovation Institute, Beihang University, Hangzhou, 311115, China
- School of Physics, Beihang University, Beijing, 100191, China
| | - Tianchao Niu
- Hangzhou International Innovation Institute, Beihang University, Hangzhou, 311115, China
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2
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Morris RJH, Lin JR, Scheerder JE, Popovici MI, Meersschaut J, Goux L, Kar GS, van der Heide P, Fleischmann C. Significant Oxygen Underestimation When Quantifying Barium-Doped SrTiO Layers by Atom Probe Tomography. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2024; 30:49-58. [PMID: 38232229 DOI: 10.1093/micmic/ozad144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 12/05/2023] [Accepted: 12/22/2023] [Indexed: 01/19/2024]
Abstract
In this paper, the capability for quantifying the composition of Ba-doped SrTiO layers from an atom probe measurement was explored. Rutherford backscattering spectrometry and time-of-flight/energy elastic recoil detection were used to benchmark the composition where the amount of titanium was intentionally varied between samples. The atom probe results showed a significant divergence from the benchmarked composition. The cause was shown to be a significant oxygen underestimation (≳14 at%). The ratio between oxygen and titanium for the samples varied between 2.6 and 12.7, while those measured by atom probe tomography were lower and covered a narrower range between 1.4 and 1.7. This difference was found to be associated with the oxygen and titanium predominantly field evaporating together as a molecular ion. The evaporation fields and bonding chemistries determined showed inconsistencies for explaining the oxygen underestimation and ion species measured. The measured ion charge state was in excellent agreement with that predicted by the Kingham postionization theory. Only by considering the measured ion species, their evaporation fields, the coordination chemistry, the analysis conditions, and some recently reported density functional theory modeling for oxide field emission were we able to postulate a field emission and oxygen neutral desorption process that may explain our results.
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Affiliation(s)
| | - Jhao-Rong Lin
- imec, Kapeldreef 75, Leuven 3001, Belgium
- Department of Physics and Astronomy, Quantum Solid-State Physics, KU Leuven, Celestijnenlaan 200D, Leuven B-3001, Belgium
| | | | | | | | | | | | | | - Claudia Fleischmann
- imec, Kapeldreef 75, Leuven 3001, Belgium
- Department of Physics and Astronomy, Quantum Solid-State Physics, KU Leuven, Celestijnenlaan 200D, Leuven B-3001, Belgium
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3
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Fathipour M, Xu Y, Rana M. Magnetron Sputtered Lead Titanates Thin Films for Pyroelectric Applications: Part 1: Epitaxial Growth, Material Characterization. MATERIALS (BASEL, SWITZERLAND) 2023; 17:221. [PMID: 38204074 PMCID: PMC10780188 DOI: 10.3390/ma17010221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 12/12/2023] [Accepted: 12/21/2023] [Indexed: 01/12/2024]
Abstract
Pyroelectric materials, are those materials with the property that in the absence of any externally applied electric field, develop a built-in spontaneous polarization in their unit cell structure. They are regarded as ideal detector elements for infrared applications because they can provide fast response time and uniform sensitivity at room temperature over all wavelengths. Crystals of the perovskite Lead Titanate (PbTiO3) family show pyroelectric characteristics and undergo structural phase transitions. They have a high Curie temperature (the temperature at which the material changes from the ferroelectric (polar) to the paraelectric (nonpolar) phase), high pyroelectric coefficient, high spontaneous polarization, low dielectric constant, and constitute important component materials not only useful for infrared detection, but also with vast applications in electronic, optic, and Micro-electromechanical systems (MEMS) devices. However, the preparation of large perfect, and pure single crystals of PbTiO3 is challenging. Additionally, difficulties arise in the application of such bulk crystals in terms of connection to processing circuits, large size, and high voltages required for their operation. A number of thin film fabrication techniques have been proposed to overcome these inadequacies, among which, magnetron sputtering has demonstrated many potentials. By addressing these aspects, the review article aims to contribute to the understanding of the challenges in the field of pyroelectric materials, highlight potential solutions, and showcase the advancements and potentials of pyroelectric perovskite series including PbZrTiO3 (PZT), PbxCa1-x (PZN-PT), etc. for which PbTiO3 is the end member. The review is presented in two parts. Part 1 focuses on material aspects, including preparation methods using magnetron sputtering and material characterization. We take a tutorial approach to discuss the progress made in epitaxial growth of lead titanate-based ceramics prepared by magnetron sputtering and examine how processing conditions may affect the crystalline quality of the growing film by linking to the properties of the substrate/buffer layer, growth substrate temperature, and the oxygen partial pressure in the gas mixture. Careful control and optimization of these parameters are crucial for achieving high-quality thin films with desired structural and morphological characteristics.
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Affiliation(s)
- Morteza Fathipour
- Division of Physics, Engineering, Mathematics and Computer Sciences & Optical Science Center for Applied Research, Delaware State University, Dover, DE 19901, USA;
| | - Yanan Xu
- Division of Physics, Engineering, Mathematics and Computer Sciences, Delaware State University, Dover, DE 19901, USA;
| | - Mukti Rana
- Division of Physics, Engineering, Mathematics and Computer Sciences & Optical Science Center for Applied Research, Delaware State University, Dover, DE 19901, USA;
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4
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Caputo M, Studniarek M, Guedes EB, Schio L, Baiseitov K, Daffé N, Bachellier N, Chikina A, Di Santo G, Verdini A, Goldoni A, Muntwiler M, Piamonteze C, Floreano L, Radovic M, Dreiser J. Charge Transfer and Orbital Reconstruction at an Organic-Oxide Interface. NANO LETTERS 2023. [PMID: 38029285 DOI: 10.1021/acs.nanolett.3c03713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2023]
Abstract
The two-dimensional electron system (2DES) located at the surface of strontium titanate (STO) and at several other STO-based interfaces has been an established platform for the study of novel physical phenomena since its discovery. Here we report how the interfacing of STO and tetracyanoquinodimethane (TCNQ) results in a charge transfer that depletes the number of free carriers at the STO surface, with a strong impact on its electronic structure. Our study paves the way for efficient tuning of the electronic properties, which promises novel applications in the framework of oxide/organic-based electronics.
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Affiliation(s)
- Marco Caputo
- Elettra Sincrotrone Trieste, s.s. 14 km 163.5 in Area Science Park, 34149 Trieste, Italy
- MAX IV Laboratory, Lund University, PO Box 118, 22100 Lund, Sweden
| | - Michał Studniarek
- Swiss Light Source, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
| | - Eduardo Bonini Guedes
- Swiss Light Source, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
| | - Luca Schio
- Laboratorio TASC, Istituto Officina dei Materiali (IOM)-CNR, Area Science Park, S.S. 14 km 163.5, 34149 Trieste, Italy
| | - Kassymkhan Baiseitov
- Swiss Light Source, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
| | - Niéli Daffé
- Swiss Light Source, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
| | - Nicolas Bachellier
- Swiss Light Source, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
| | - Alla Chikina
- Swiss Light Source, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
| | - Giovanni Di Santo
- Elettra Sincrotrone Trieste, s.s. 14 km 163.5 in Area Science Park, 34149 Trieste, Italy
| | - Alberto Verdini
- Laboratorio TASC, Istituto Officina dei Materiali (IOM)-CNR, Area Science Park, S.S. 14 km 163.5, 34149 Trieste, Italy
| | - Andrea Goldoni
- Elettra Sincrotrone Trieste, s.s. 14 km 163.5 in Area Science Park, 34149 Trieste, Italy
| | - Matthias Muntwiler
- Swiss Light Source, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
| | - Cinthia Piamonteze
- Swiss Light Source, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
| | - Luca Floreano
- Laboratorio TASC, Istituto Officina dei Materiali (IOM)-CNR, Area Science Park, S.S. 14 km 163.5, 34149 Trieste, Italy
| | - Milan Radovic
- Swiss Light Source, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
| | - Jan Dreiser
- Swiss Light Source, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
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Nethwewala A, Lee H, Li J, Briggeman M, Pai YY, Eom K, Eom CB, Irvin P, Levy J. Electron pairing and nematicity in LaAlO 3/SrTiO 3 nanostructures. Nat Commun 2023; 14:7657. [PMID: 37996464 PMCID: PMC10667274 DOI: 10.1038/s41467-023-43539-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 11/13/2023] [Indexed: 11/25/2023] Open
Abstract
Strongly correlated electronic systems exhibit a wealth of unconventional behavior stemming from strong electron-electron interactions. The LaAlO3/SrTiO3 (LAO/STO) heterostructure supports rich and varied low-temperature transport characteristics including low-density superconductivity, and electron pairing without superconductivity for which the microscopic origins is still not understood. LAO/STO also exhibits inexplicable signatures of electronic nematicity via nonlinear and anomalous Hall effects. Nanoscale control over the conductivity of the LAO/STO interface enables mesoscopic experiments that can probe these effects and address their microscopic origins. Here we report a direct correlation between electron pairing without superconductivity, anomalous Hall effect and electronic nematicity in quasi-1D ballistic nanoscale LAO/STO Hall crosses. The characteristic magnetic field at which the Hall coefficient changes directly coincides with the depairing of non-superconducting pairs showing a strong correlation between the two distinct phenomena. Angle-dependent Hall measurements further reveal an onset of electronic nematicity that again coincides with the electron pairing transition, unveiling a rotational symmetry breaking due to the transition from paired to unpaired phases at the interface. The results presented here highlights the influence of preformed electron pairs on the transport properties of LAO/STO and provide evidence of the elusive pairing "glue" that gives rise to electron pairing in SrTiO3-based systems.
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Affiliation(s)
- Aditi Nethwewala
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA, 15260, USA
| | - Hyungwoo Lee
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Jianan Li
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA, 15260, USA
| | - Megan Briggeman
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA, 15260, USA
| | - Yun-Yi Pai
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA, 15260, USA
| | - Kitae Eom
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Chang-Beom Eom
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Patrick Irvin
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA, 15260, USA
| | - Jeremy Levy
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, 15260, USA.
- Pittsburgh Quantum Institute, Pittsburgh, PA, 15260, USA.
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, 15260, USA.
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6
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Gorshkov VN, Stretovych MO, Semeniuk VF, Kruglenko MP, Semeniuk NI, Styopkin VI, Gabovich AM, Boiger GK. Hierarchical Structuring of Black Silicon Wafers by Ion-Flow-Stimulated Roughening Transition: Fundamentals and Applications for Photovoltaics. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2715. [PMID: 37836356 PMCID: PMC10574651 DOI: 10.3390/nano13192715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 09/27/2023] [Accepted: 10/02/2023] [Indexed: 10/15/2023]
Abstract
Ion-flow-stimulated roughening transition is a phenomenon that may prove useful in the hierarchical structuring of nanostructures. In this work, we have investigated theoretically and experimentally the surface texturing of single-crystal and multi-crystalline silicon wafers irradiated using ion-beam flows. In contrast to previous studies, ions had relatively low energies, whereas flow densities were high enough to induce a quasi-liquid state in the upper silicon layers. The resulting surface modifications reduced the wafer light reflectance to values characteristic of black silicon, widely used in solar energetics. Features of nanostructures on different faces of silicon single crystals were studied numerically based on the mesoscopic Monte Carlo model. We established that the formation of nano-pyramids, ridges, and twisting dune-like structures is due to the stimulated roughening transition effect. The aforementioned variety of modified surface morphologies arises due to the fact that the effects of stimulated surface diffusion of atoms and re-deposition of free atoms on the wafer surface from the near-surface region are manifested to different degrees on different Si faces. It is these two factors that determine the selection of the allowable "trajectories" (evolution paths) of the thermodynamic system along which its Helmholtz free energy, F, decreases, concomitant with an increase in the surface area of the wafer and the corresponding changes in its internal energy, U (dU>0), and entropy, S (dS>0), so that dF=dU - TdS<0, where T is the absolute temperature. The basic theoretical concepts developed were confirmed in experimental studies, the results of which showed that our method could produce, abundantly, black silicon wafers in an environmentally friendly manner compared to traditional chemical etching.
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Affiliation(s)
- Vyacheslav N. Gorshkov
- Igor Sikorsky Kyiv Polytechnic Institute, National Technical University of Ukraine, Prospect Beresteiskyi, 37, 03056 Kyiv, Ukraine;
- G.V. Kurdyumov Institute for Metal Physics, National Academy of Sciences of Ukraine, 36 Academician Vernadsky Boulevard, 03142 Kyiv, Ukraine
- Department of Mechanical and Aerospace Engineering, University of Liverpool, Liverpool L69 3GH, UK
| | - Mykola O. Stretovych
- Igor Sikorsky Kyiv Polytechnic Institute, National Technical University of Ukraine, Prospect Beresteiskyi, 37, 03056 Kyiv, Ukraine;
| | - Valerii F. Semeniuk
- Institute of Physics of the Ukrainian National Academy of Sciences, Nauka Avenue, 46, 03028 Kyiv, Ukraine; (V.F.S.); (M.P.K.); (V.I.S.); (A.M.G.)
- GreSem Innovation LLC, Vyzvolyteliv Avenue, 13, 02660 Kyiv, Ukraine;
| | - Mikhail P. Kruglenko
- Institute of Physics of the Ukrainian National Academy of Sciences, Nauka Avenue, 46, 03028 Kyiv, Ukraine; (V.F.S.); (M.P.K.); (V.I.S.); (A.M.G.)
- GreSem Innovation LLC, Vyzvolyteliv Avenue, 13, 02660 Kyiv, Ukraine;
| | | | - Victor I. Styopkin
- Institute of Physics of the Ukrainian National Academy of Sciences, Nauka Avenue, 46, 03028 Kyiv, Ukraine; (V.F.S.); (M.P.K.); (V.I.S.); (A.M.G.)
| | - Alexander M. Gabovich
- Institute of Physics of the Ukrainian National Academy of Sciences, Nauka Avenue, 46, 03028 Kyiv, Ukraine; (V.F.S.); (M.P.K.); (V.I.S.); (A.M.G.)
| | - Gernot K. Boiger
- ICP Institute of Computational Physics, ZHAW Zürich University of Applied Sciences, Wildbachstrasse 21, CH-8401 Winterthur, Switzerland
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7
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Liu X, Zhou T, Qin Z, Ma C, Lu F, Liu T, Li J, Wei SH, Cheng G, Liu WT. Nonlinear optical phonon spectroscopy revealing polaronic signatures of the LaAlO 3/SrTiO 3 interface. SCIENCE ADVANCES 2023; 9:eadg7037. [PMID: 37294751 DOI: 10.1126/sciadv.adg7037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 05/04/2023] [Indexed: 06/11/2023]
Abstract
We report the direct observation of lattice phonons confined at LaAlO3/SrTiO3 (LAO/STO) interfaces and STO surfaces using the sum-frequency phonon spectroscopy. This interface-specific nonlinear optical technique unveiled phonon modes localized within a few monolayers at the interface, with inherent sensitivity to the coupling between lattice and charge degrees of freedom. Spectral evolution across the insulator-to-metal transition at LAO/STO interface revealed an electronic reconstruction at the subcritical LAO thickness, as well as strong polaronic signatures upon formation of the two-dimensional electron gas. We further discovered a characteristic lattice mode from interfacial oxygen vacancies, enabling us to probe such important structural defects in situ. Our study provides a unique perspective on many-body interactions at the correlated oxide interfaces.
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Affiliation(s)
- Xinyi Liu
- Physics Department, State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures [Ministry of Education (MOE)], Fudan University, Shanghai 200433, China
| | - Tao Zhou
- Physics Department, State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures [Ministry of Education (MOE)], Fudan University, Shanghai 200433, China
| | - Zhiyuan Qin
- CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Changjian Ma
- CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China
| | - Fanjin Lu
- Physics Department, State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures [Ministry of Education (MOE)], Fudan University, Shanghai 200433, China
| | - Tongying Liu
- Physics Department, State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures [Ministry of Education (MOE)], Fudan University, Shanghai 200433, China
| | - Jiashi Li
- Physics Department, State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures [Ministry of Education (MOE)], Fudan University, Shanghai 200433, China
| | - Su-Huai Wei
- Beijing Computational Science Research Center, Beijing 100193, China
| | - Guanglei Cheng
- CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Wei-Tao Liu
- Physics Department, State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures [Ministry of Education (MOE)], Fudan University, Shanghai 200433, China
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8
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Huang J, Dai S, Xu C, Du Y, Xu Z, Han K, Xu L, Wu W, Chen P, Huang Z. Capping-layer-mediated lattice mismatch and redox reaction in SrTiO 3-based bilayers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35. [PMID: 37059113 DOI: 10.1088/1361-648x/accd37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 04/14/2023] [Indexed: 05/16/2023]
Abstract
It is well known that the traditional two-dimensional electron system (2DES) hosted by the SrTiO3substrate can exhibit diverse electronic states by modifying the capping layer in heterostructures. However, such capping layer engineering is less studied in the SrTiO3-layer-carried 2DES (or bilayer 2DES), which is different from the traditional one on transport properties but more applicable to the thin-film devices. Here, several SrTiO3bilayers are fabricated by growing various crystalline and amorphous oxide capping layers on the epitaxial SrTiO3layers. For the crystalline bilayer 2DES, the monotonical reduction on the interfacial conductance, as well as carrier mobility, is recorded on increasing the lattice mismatch between the capping layers and epitaxial SrTiO3layer. The mobility edge raised by the interfacial disorders is highlighted in the crystalline bilayer 2DES. On the other hand, when increasing the concentration of Al with high oxygen affinity in the capping layer, the amorphous bilayer 2DES becomes more conductive accompanied by the enhanced carrier mobility but almost constant carrier density. This observation cannot be explained by the simple redox-reaction model, and the interfacial charge screening and band bending need to be considered. Moreover, when the capping oxide layers have the same chemical composition but with different forms, the crystalline 2DES with a large lattice mismatch is more insulating than its amorphous counterpart, and vice versa. Our results shed some light on understanding the different dominant role in forming the bilayer 2DES using crystalline and amorphous oxide capping layer, which may be applicable in designing other functional oxide interfaces.
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Affiliation(s)
- Jingwen Huang
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, People's Republic of China
| | - Song Dai
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, People's Republic of China
| | - Chengcheng Xu
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, People's Republic of China
| | - Yongyi Du
- Stony Brook Institute at Anhui University, Anhui University, Hefei 230039, People's Republic of China
| | - Zhipeng Xu
- Stony Brook Institute at Anhui University, Anhui University, Hefei 230039, People's Republic of China
| | - Kun Han
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, People's Republic of China
| | - Liqiang Xu
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, People's Republic of China
| | - Wenbin Wu
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Pingfan Chen
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, People's Republic of China
| | - Zhen Huang
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, People's Republic of China
- Stony Brook Institute at Anhui University, Anhui University, Hefei 230039, People's Republic of China
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9
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Prifti E, Buban JP, Thind AS, Klie RF. Variational Convolutional Autoencoders for Anomaly Detection in Scanning Transmission Electron Microscopy. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2205977. [PMID: 36651114 DOI: 10.1002/smll.202205977] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 12/08/2022] [Indexed: 06/17/2023]
Abstract
Identifying point defects and other structural anomalies using scanning transmission electron microscopy (STEM) is important to understand a material's properties caused by the disruption of the regular pattern of crystal lattice. Due to improvements in instrumentation stability and electron optics, atomic-resolution images with a field of view of several hundred nanometers can now be routinely acquired at 1-10 Hz frame rates and such data, which often contain thousands of atomic columns, need to be analyzed. To date, image analysis is performed largely manually, but recent developments in computer vision (CV) and machine learning (ML) now enable automated analysis of atomic structures and associated defects. Here, the authors report on how a Convolutional Variational Autoencoder (CVAE) can be utilized to detect structural anomalies in atomic-resolution STEM images. Specifically, the training set is limited to perfect crystal images , and the performance of a CVAE in differentiating between single-crystal bulk data or point defects is demonstrated. It is found that the CVAE can reproduce the perfect crystal data but not the defect input data. The disagreesments between the CVAE-predicted data for defects allows for a clear and automatic distinction and differentiation of several point defect types.
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Affiliation(s)
- Enea Prifti
- Department of Physics, University of Illinois Chicago, 845 W Taylor Street, Chicago, IL, 60607, USA
| | - James P Buban
- Department of Physics, University of Illinois Chicago, 845 W Taylor Street, Chicago, IL, 60607, USA
| | - Arashdeep Singh Thind
- Department of Physics, University of Illinois Chicago, 845 W Taylor Street, Chicago, IL, 60607, USA
| | - Robert F Klie
- Department of Physics, University of Illinois Chicago, 845 W Taylor Street, Chicago, IL, 60607, USA
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10
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Trama M, Cataudella V, Perroni CA, Romeo F, Citro R. Effect of Confinement and Coulomb Interactions on the Electronic Structure of the (111) LaAlO 3/SrTiO 3 Interface. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:819. [PMID: 36903699 PMCID: PMC10005189 DOI: 10.3390/nano13050819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 02/13/2023] [Accepted: 02/20/2023] [Indexed: 06/18/2023]
Abstract
A tight binding supercell approach is used for the calculation of the electronic structure of the (111) LaAlO3/SrTiO3 interface. The confinement potential at the interface is evaluated solving a discrete Poisson equation by means of an iterative method. In addition to the effect of the confinement, local Hubbard electron-electron terms are included at the mean-field level within a fully self-consistent procedure. The calculation carefully describes how the two-dimensional electron gas arises from the quantum confinement of electrons near the interface due to the band bending potential. The resulting electronic sub-bands and Fermi surfaces show full agreement with the electronic structure determined by angle-resolved photoelectron spectroscopy experiments. In particular, we analyse how the effect of local Hubbard interactions change the density distribution over the layers from the interface to the bulk. Interestingly, the two-dimensional electron gas at the interface is not depleted by local Hubbard interactions which indeed induce an enhancement of the electron density between the first layers and the bulk.
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Affiliation(s)
- Mattia Trama
- Physics Department “E.R. Caianiello”, Universitá degli Studi di Salerno, Via Giovanni Paolo II, 132, I-84084 Fisciano, Italy
- INFN—Sezione di Napoli, Complesso Universitario Monte S. Angelo, I-80126 Naples, Italy
- Institute for Theoretical Solid State Physics, IFW Dresden, Helmholtzstr. 20, 01069 Dresden, Germany
| | - Vittorio Cataudella
- Physics Department “Ettore Pancini”, Universitá degli Studi di Napoli “Federico II”, Complesso Universitario Monte S. Angelo, Via Cintia, I-80126 Naples, Italy
- CNR-SPIN Napoli Unit, Complesso Universitario Monte S. Angelo, Via Cintia, I-80126 Naples, Italy
| | - Carmine Antonio Perroni
- Physics Department “Ettore Pancini”, Universitá degli Studi di Napoli “Federico II”, Complesso Universitario Monte S. Angelo, Via Cintia, I-80126 Naples, Italy
- CNR-SPIN Napoli Unit, Complesso Universitario Monte S. Angelo, Via Cintia, I-80126 Naples, Italy
| | - Francesco Romeo
- Physics Department “E.R. Caianiello”, Universitá degli Studi di Salerno, Via Giovanni Paolo II, 132, I-84084 Fisciano, Italy
| | - Roberta Citro
- Physics Department “E.R. Caianiello”, Universitá degli Studi di Salerno, Via Giovanni Paolo II, 132, I-84084 Fisciano, Italy
- INFN—Sezione di Napoli, Complesso Universitario Monte S. Angelo, I-80126 Naples, Italy
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11
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Wang Q, Gu Y, Chen C, Pan F, Song C. Oxide Spintronics as a Knot of Physics and Chemistry: Recent Progress and Opportunities. J Phys Chem Lett 2022; 13:10065-10075. [PMID: 36264651 DOI: 10.1021/acs.jpclett.2c02634] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Transition-metal oxides (TMOs) constitute a key material family in spintronics because of mutually coupled degrees of freedom and tunable magneto-ionic properties. In this Perspective, we consider oxide spintronics as a knot of physics and chemistry and mainly discuss two current hot topics: spin-charge interconversion and magneto-ionics. First, spin-charge interconversion is focused on oxide films and heterostructures including 4d/5d heavy metal oxides (e.g., SrIrO3) and two-dimensional electron gases. Based on spin-charge interconversion, charge currents can be transformed to spin currents and generate spin-orbit torque in oxide/metal and all-oxide heterostructures. Additionally, the voltage control of magnetism in TMOs by the magneto-ionic pathway has rapidly accelerated during the past few years due to the versatile advantages of effective control, nonvolatile nature, low power cost, etc. Typical magneto-ionic oxide systems and corresponding physicochemical mechanisms will be discussed. Finally, further developments of oxide spintronics are envisioned, including material discovery, physics exploration, device design, and manipulation methods.
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Affiliation(s)
- Qian Wang
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing100084, China
| | - Youdi Gu
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing100084, China
| | - Chong Chen
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing100084, China
| | - Feng Pan
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing100084, China
| | - Cheng Song
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing100084, China
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12
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Yu M, Liu C, Yang D, Yan X, Du Q, Fong DD, Bhattacharya A, Irvin P, Levy J. Nanoscale Control of the Metal-Insulator Transition at LaAlO 3/KTaO 3 Interfaces. NANO LETTERS 2022; 22:6062-6068. [PMID: 35862274 DOI: 10.1021/acs.nanolett.2c00673] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Recent reports of superconductivity at KTaO3 (KTO) (110) and (111) interfaces have sparked intense interest due to the relatively high critical temperature as well as other properties that distinguish this system from the more extensively studied SrTiO3 (STO)-based heterostructures. Here, we report the reconfigurable creation of conducting structures at intrinsically insulating LaAlO3/KTO(110) and (111) interfaces. Devices are created using two distinct methods previously developed for STO-based heterostructures: (1) conductive atomic-force microscopy lithography and (2) ultralow-voltage electron-beam lithography. At low temperatures, KTO(110)-based devices show superconductivity that is tunable by an applied back gate. A one-dimensional nanowire device shows single-electron-transistor (SET) behavior. A KTO(111)-based device is metallic but does not become superconducting. These reconfigurable methods of creating nanoscale devices in KTO-based heterostructures offer new avenues for investigating mechanisms of superconductivity as well as development of quantum devices that incorporate strong spin-orbit interactions, superconducting behavior, and nanoscale dimensions.
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Affiliation(s)
- Muqing Yu
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Pittsburgh Quantum Institute, Pittsburgh, Pennsylvania 15260, United States
| | - Changjiang Liu
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Dengyu Yang
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Pittsburgh Quantum Institute, Pittsburgh, Pennsylvania 15260, United States
| | - Xi Yan
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Qianheng Du
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Dillon D Fong
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Anand Bhattacharya
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Patrick Irvin
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Pittsburgh Quantum Institute, Pittsburgh, Pennsylvania 15260, United States
| | - Jeremy Levy
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Pittsburgh Quantum Institute, Pittsburgh, Pennsylvania 15260, United States
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13
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Tunable Spin and Orbital Edelstein Effect at (111) LaAlO3/SrTiO3 Interface. NANOMATERIALS 2022; 12:nano12142494. [PMID: 35889717 PMCID: PMC9318607 DOI: 10.3390/nano12142494] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 07/18/2022] [Accepted: 07/19/2022] [Indexed: 12/04/2022]
Abstract
Converting charge current into spin current is one of the main mechanisms exploited in spintronics. One prominent example is the Edelstein effect, namely, the generation of a magnetization in response to an external electric field, which can be realized in systems with lack of inversion symmetry. If a system has electrons with an orbital angular momentum character, an orbital magnetization can be generated by the applied electric field, giving rise to the so-called orbital Edelstein effect. Oxide heterostructures are the ideal platform for these effects due to the strong spin–orbit coupling and the lack of inversion symmetries. Beyond a gate-tunable spin Edelstein effect, we predict an orbital Edelstein effect an order of magnitude larger then the spin one at the (111) LaAlO3/SrTiO3 interface for very low and high fillings. We model the material as a bilayer of t2g orbitals using a tight-binding approach, whereas transport properties are obtained in the Boltzmann approach. We give an effective model at low filling, which explains the non-trivial behaviour of the Edelstein response, showing that the hybridization between the electronic bands crucially impacts the Edelstein susceptibility.
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14
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Erlandsen R, Dahm RT, Trier F, Scuderi M, Di Gennaro E, Sambri A, Reffeldt Kirchert CK, Pryds N, Granozio FM, Jespersen TS. A Two-Dimensional Superconducting Electron Gas in Freestanding LaAlO 3/SrTiO 3 Micromembranes. NANO LETTERS 2022; 22:4758-4764. [PMID: 35679577 DOI: 10.1021/acs.nanolett.2c00992] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Freestanding oxide membranes constitute an intriguing material platform for new functionalities and allow integration of oxide electronics with technologically important platforms such as silicon. Sambri et al. recently reported a method to fabricate freestanding LaAlO3/SrTiO3 (LAO/STO) membranes by spalling of strained heterostructures. Here, we first develop a scheme for the high-yield fabrication of membrane devices on silicon. Second, we show that the membranes exhibit metallic conductivity and a superconducting phase below ∼200 mK. Using anisotropic magnetotransport we extract the superconducting phase coherence length ξ ≈ 36-80 nm and establish an upper bound on the thickness of the superconducting electron gas d ≈ 17-33 nm, thus confirming its two-dimensional character. Finally, we show that the critical current can be modulated using a silicon-based backgate. The ability to form superconducting nanostructures of LAO/STO membranes, with electronic properties similar to those of the bulk counterpart, opens opportunities for integrating oxide nanoelectronics with silicon-based architectures.
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Affiliation(s)
- Ricci Erlandsen
- Department of Energy Conversion and Storage, Technical University of Denmark, Fysikvej, Building 310, 2800 Kgs. Lyngby, Denmark
| | - Rasmus Tindal Dahm
- Department of Energy Conversion and Storage, Technical University of Denmark, Fysikvej, Building 310, 2800 Kgs. Lyngby, Denmark
| | - Felix Trier
- Department of Energy Conversion and Storage, Technical University of Denmark, Fysikvej, Building 310, 2800 Kgs. Lyngby, Denmark
| | - Mario Scuderi
- Institute for Microelectronics and Microsystems (CNR-IMM), Strada VIII n.5 Zona Industriale, I-95121 Catania, Italy
| | - Emiliano Di Gennaro
- Dipartimento di Fisica "Ettore Pancini", Università degli Studi di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Via Cinthia, I-80126 Napoli, Italy
| | - Alessia Sambri
- CNR-SPIN, Complesso Universitario di Monte Sant'Angelo, Via Cinthia, I-80126 Napoli, Italy
| | | | - Nini Pryds
- Department of Energy Conversion and Storage, Technical University of Denmark, Fysikvej, Building 310, 2800 Kgs. Lyngby, Denmark
| | - Fabio Miletto Granozio
- CNR-SPIN, Complesso Universitario di Monte Sant'Angelo, Via Cinthia, I-80126 Napoli, Italy
| | - Thomas Sand Jespersen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
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15
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Mikheev E, Zimmerling T, Estry A, Moll PJW, Goldhaber-Gordon D. Ionic Liquid Gating of SrTiO 3 Lamellas Fabricated with a Focused Ion Beam. NANO LETTERS 2022; 22:3872-3878. [PMID: 35576585 DOI: 10.1021/acs.nanolett.1c04447] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In this work, we combine two previously incompatible techniques for defining electronic devices: shaping three-dimensional crystals by focused ion beam (FIB), and two-dimensional electrostatic accumulation of charge carriers. The principal challenge for this integration is nanometer-scale surface damage inherent to any FIB-based fabrication. We address this by using a sacrificial protective layer to preserve a selected pristine surface. The test case presented here is accumulation of 2D carriers by ionic liquid gating at the surface of a micron-scale SrTiO3 lamella. Preservation of surface quality is reflected in superconductivity of the accumulated carriers. This technique opens new avenues for realizing electrostatic charge tuning in materials that are not available as large or exfoliatable single crystals, and for patterning the geometry of the accumulated carriers.
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Affiliation(s)
- Evgeny Mikheev
- Department of Physics, Stanford University, Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Tino Zimmerling
- Max-Planck-Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - Amelia Estry
- Max-Planck-Institute for Chemical Physics of Solids, 01187 Dresden, Germany
- Laboratory of Quantum Materials (QMAT), Institute of Materials (IMX), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Philip J W Moll
- Max-Planck-Institute for Chemical Physics of Solids, 01187 Dresden, Germany
- Laboratory of Quantum Materials (QMAT), Institute of Materials (IMX), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - David Goldhaber-Gordon
- Department of Physics, Stanford University, Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
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16
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Gupta A, Silotia H, Kumari A, Dumen M, Goyal S, Tomar R, Wadehra N, Ayyub P, Chakraverty S. KTaO 3 -The New Kid on the Spintronics Block. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2106481. [PMID: 34961972 DOI: 10.1002/adma.202106481] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 11/16/2021] [Indexed: 06/14/2023]
Abstract
Long after the heady days of high-temperature superconductivity, the oxides came back into the limelight in 2004 with the discovery of the 2D electron gas (2DEG) in SrTiO3 (STO) and several heterostructures based on it. Not only do these materials exhibit interesting physics, but they have also opened up new vistas in oxide electronics and spintronics. However, much of the attention has recently shifted to KTaO3 (KTO), a material with all the "good" properties of STO (simple cubic structure, high mobility, etc.) but with the additional advantage of a much larger spin-orbit coupling. In this state-of-the-art review of the fascinating world of KTO, it is attempted to cover the remarkable progress made, particularly in the last five years. Certain unsolved issues are also indicated, while suggesting future research directions as well as potential applications. The range of physical phenomena associated with the 2DEG trapped at the interfaces of KTO-based heterostructures include spin polarization, superconductivity, quantum oscillations in the magnetoresistance, spin-polarized electron transport, persistent photocurrent, Rashba effect, topological Hall effect, and inverse Edelstein Effect. It is aimed to discuss, on a single platform, the various fabrication techniques, the exciting physical properties and future application possibilities of this family of materials.
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Affiliation(s)
- Anshu Gupta
- Quantum Materials and Devices Unit, Institute of Nano Science and Technology, Sector-81, Mohali, Punjab, 140306, India
| | - Harsha Silotia
- Quantum Materials and Devices Unit, Institute of Nano Science and Technology, Sector-81, Mohali, Punjab, 140306, India
| | - Anamika Kumari
- Quantum Materials and Devices Unit, Institute of Nano Science and Technology, Sector-81, Mohali, Punjab, 140306, India
| | - Manish Dumen
- Quantum Materials and Devices Unit, Institute of Nano Science and Technology, Sector-81, Mohali, Punjab, 140306, India
| | - Saveena Goyal
- Quantum Materials and Devices Unit, Institute of Nano Science and Technology, Sector-81, Mohali, Punjab, 140306, India
| | - Ruchi Tomar
- Quantum Materials and Devices Unit, Institute of Nano Science and Technology, Sector-81, Mohali, Punjab, 140306, India
| | - Neha Wadehra
- Quantum Materials and Devices Unit, Institute of Nano Science and Technology, Sector-81, Mohali, Punjab, 140306, India
| | - Pushan Ayyub
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Mumbai, India
| | - Suvankar Chakraverty
- Quantum Materials and Devices Unit, Institute of Nano Science and Technology, Sector-81, Mohali, Punjab, 140306, India
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17
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Chiu CC, Ho SZ, Lee JM, Shao YC, Shen Y, Liu YC, Chang YW, Zheng YZ, Huang R, Chang CF, Kuo CY, Duan CG, Huang SW, Yang JC, Chuang YD. Presence of Delocalized Ti 3d Electrons in Ultrathin Single-Crystal SrTiO 3. NANO LETTERS 2022; 22:1580-1586. [PMID: 35073104 DOI: 10.1021/acs.nanolett.1c04434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Strontium titanate (STO), with a wide spectrum of emergent properties such as ferroelectricity and superconductivity, has received significant attention in the community of strongly correlated materials. In the strain-free STO film grown on the SrRuO3 buffer layer, the existing polar nanoregions can facilitate room-temperature ferroelectricity when the STO film thickness approaches 10 nm. Here we show that around this thickness scale, the freestanding STO films without the influence of a substrate show the tetragonal structure at room temperature, contrasting with the cubic structure seen in bulk form. The spectroscopic measurements reveal the modified Ti-O orbital hybridization that causes the Ti ion to deviate from its nominal 4+ valency (3d0 configuration) with excess delocalized 3d electrons. Additionally, the Ti ion in TiO6 octahedron exhibits an off-center displacement. The inherent symmetry lowering in ultrathin freestanding films offers an alternative way to achieve tunable electronic structures that are of paramount importance for future technological applications.
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Affiliation(s)
- Chun-Chien Chiu
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - Sheng-Zhu Ho
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - Jenn-Min Lee
- MAX IV Laboratory, Lund University, P.O. Box 118, 221 00 Lund, Sweden
| | - Yu-Cheng Shao
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Yang Shen
- Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronics, East China Normal University, Shanghai 200241, China
| | - Yu-Chen Liu
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - Yao-Wen Chang
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - Yun-Zhe Zheng
- Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronics, East China Normal University, Shanghai 200241, China
| | - Rong Huang
- Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronics, East China Normal University, Shanghai 200241, China
| | - Chun-Fu Chang
- Max-Planck Institute for Chemical Physics of Solids, Dresden 01187, Germany
| | - Chang-Yang Kuo
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
- Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan
| | - Chun-Gang Duan
- Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronics, East China Normal University, Shanghai 200241, China
| | - Shih-Wen Huang
- MAX IV Laboratory, Lund University, P.O. Box 118, 221 00 Lund, Sweden
- Swiss Light Source, Paul Scherrer Institut, CH5232 Villigen PSI, Switzerland
| | - Jan-Chi Yang
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
- Center for Quantum Frontiers of Research & Technology (QFort), National Cheng Kung University, Tainan 70101, Taiwan
| | - Yi-De Chuang
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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18
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Navas D, Fuentes S, Castro-Alvarez A, Chavez-Angel E. Review on Sol-Gel Synthesis of Perovskite and Oxide Nanomaterials. Gels 2021; 7:275. [PMID: 34940335 PMCID: PMC8700921 DOI: 10.3390/gels7040275] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 12/10/2021] [Accepted: 12/15/2021] [Indexed: 11/16/2022] Open
Abstract
Sol-Gel is a low cost, well-established and flexible synthetic route to produce a wide range of micro- and nanostructures. Small variations in pH, temperature, precursors, time, pressure, atmosphere, among others, can lead to a wide family of compounds that share the same molecular structures. In this work, we present a general review of the synthesis of LaMnO3, SrTiO3, BaTiO3 perovskites and zinc vanadium oxides nanostructures based on Sol-Gel method. We discuss how small changes in the parameters of the synthesis can modify the morphology, shape, size, homogeneity, aggregation, among others, of the products. We also discuss the different precursors, solvents, working temperature, reaction times used throughout the synthesis. In the last section, we present novel uses of Sol-Gel with organic materials with emphasis on carbon-based compounds. All with a perspective to improve the method for future applications in different technological fields.
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Affiliation(s)
- Daniel Navas
- Departamento de Química, Facultad de Ciencias Naturales, Matemática y del Medio Ambiente, Universidad Tecnológica Metropolitana, Las Palmeras 3360, Ñuñoa, Santiago 7800003, Chile;
| | - Sandra Fuentes
- Departamento de Ciencias Farmaceúticas, Facultad de Ciencias, Universidad Católica del Norte, Av. Angamos 0610, Antofagasta 1270709, Chile
- Center for the Development of Nanoscience and Nanotechnology, CEDENNA, Av. Libertador Bernardo O’Higgins 3363, Santiago 9160000, Chile
| | - Alejandro Castro-Alvarez
- Laboratorio de Bioproductos Farmacéuticos y Cosméticos, Centro de Excelencia en Medicina Traslacional, Facultad de Medicina, Universidad de La Frontera, Av. Francisco Salazar 01145, Temuco 4780000, Chile;
| | - Emigdio Chavez-Angel
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
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19
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Flexible zirconium doped strontium titanate nanofibrous membranes with enhanced visible-light photocatalytic performance and antibacterial activities. J Colloid Interface Sci 2021; 600:127-137. [PMID: 34010770 DOI: 10.1016/j.jcis.2021.05.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 05/02/2021] [Accepted: 05/03/2021] [Indexed: 11/20/2022]
Abstract
Constructing flexible perovskite structured ceramic fibrous materials would potentially facilitate applications of photocatalysis, wearable devices, and energy storage. However, current perovskite structured ceramic fibrous materials were fragile with small deformation resistance, which have limited their wide applications. Herein, flexible zirconium doped strontium titanate (ZSTO) nanofibrous membranes were fabricated via combining sol-gel and electrospinning methods. The microstructures (pore and crystal) of ZSTO nanofibers were affected by zirconium doping contents and closely relevant to flexibility of resultant membranes. The probable mechanism for flexibility of ZSTO nanofibrous membranes was presented. Furthermore, the silver phosphate modified ZSTO (AZSTO) exhibited superior photocatalytic performance towards tetracycline hydrochloride (TCHC) and antibacterial performance towards Gram-negative and Gram-positive bacteria with visible-light irradiation, including 85% degradation towards TCHC within 60 min, >99.99% inhibition rate and > 3 mm inhibition zone against Gram bacteria. Furthermore, the·superoxide free radical (O2-) and holes played significant roles in the degradation of TCHC that verified by radical scavenger experiment. Additionally, the membranes exhibited good reusability over five cycles without tedious recycling operations needed for micro/nanoparticle-based catalysts. The successful fabrication of ZSTO nanofibrous membranes would provide a new insight into photocatalysts, antibacterial materials, and wearable device.
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20
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Dubnack O, Müller FA. Oxidic 2D Materials. MATERIALS 2021; 14:ma14185213. [PMID: 34576436 PMCID: PMC8469416 DOI: 10.3390/ma14185213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 09/07/2021] [Accepted: 09/08/2021] [Indexed: 11/18/2022]
Abstract
The possibility of producing stable thin films, only a few atomic layers thick, from a variety of materials beyond graphene has led to two-dimensional (2D) materials being studied intensively in recent years. By reducing the layer thickness and approaching the crystallographic monolayer limit, a variety of unexpected and technologically relevant property phenomena were observed, which also depend on the subsequent arrangement and possible combination of individual layers to form heterostructures. These properties can be specifically used for the development of multifunctional devices, meeting the requirements of the advancing miniaturization of modern manufacturing technologies and the associated need to stabilize physical states even below critical layer thicknesses of conventional materials in the fields of electronics, magnetism and energy conversion. Differences in the structure of potential two-dimensional materials result in decisive influences on possible growth methods and possibilities for subsequent transfer of the thin films. In this review, we focus on recent advances in the rapidly growing field of two-dimensional materials, highlighting those with oxidic crystal structure like perovskites, garnets and spinels. In addition to a selection of well-established growth techniques and approaches for thin film transfer, we evaluate in detail their application potential as free-standing monolayers, bilayers and multilayers in a wide range of advanced technological applications. Finally, we provide suggestions for future developments of this promising research field in consideration of current challenges regarding scalability and structural stability of ultra-thin films.
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Affiliation(s)
- Oliver Dubnack
- Otto Schott Institute of Materials Research (OSIM), Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany;
| | - Frank A. Müller
- Otto Schott Institute of Materials Research (OSIM), Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany;
- Center for Energy and Environmental Chemistry Jena (CEEC Jena), Friedrich Schiller University Jena, Philosophenweg 7a, 07743 Jena, Germany
- Correspondence:
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21
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Zhou X, Liu Z. Nature of electrons from oxygen vacancies and polar catastrophe at LaAlO 3/SrTiO 3interfaces. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:435601. [PMID: 34320477 DOI: 10.1088/1361-648x/ac1883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 07/28/2021] [Indexed: 06/13/2023]
Abstract
The relative significance of quantum conductivity correction and magnetic nature of electrons in understanding the intriguing low-temperature resistivity minimum and negative magnetoresistance (MR) of the two-dimensional electron gas at LaAlO3/SrTiO3interfaces has been a long outstanding issue since its discovery. Here we report a comparative magnetotransport study on amorphous and oxygen-annealed crystalline LaAlO3/SrTiO3heterostructures at a relatively high-temperature range, where the orbital scattering is largely suppressed by thermal fluctuations. Despite of a predominantly negative out-of-plane MR effect for both, the magnetotransport is isotropic for amorphous LaAlO3/SrTiO3while strongly anisotropic and well falls into a two-dimensional quantum correction frame for annealed crystalline LaAlO3/SrTiO3. These results clearly indicate that a large portion of electrons from oxygen vacancies are localized at low temperatures, serving as magnetic centers, while the electrons from the polar field are only weakly localized due to constructive interference between time-reversed electron paths in the clean limit and no signature of magnetic nature is visible.
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Affiliation(s)
- Xiaorong Zhou
- School of Materials Science and Engineering, Beihang University, Beijing 100191, People's Republic of China
| | - Zhiqi Liu
- School of Materials Science and Engineering, Beihang University, Beijing 100191, People's Republic of China
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22
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Jin MJ, Um DS, Ohnishi K, Komori S, Stelmashenko N, Choe D, Yoo JW, Robinson JWA. Pure Spin Currents Driven by Colossal Spin-Orbit Coupling on Two-Dimensional Surface Conducting SrTiO 3. NANO LETTERS 2021; 21:6511-6517. [PMID: 34320314 DOI: 10.1021/acs.nanolett.1c01607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Spin accumulation is generated by passing a charge current through a ferromagnetic layer and sensed by other ferromagnetic layers downstream. Pure spin currents can also be generated in which spin currents flow and are detected as a nonlocal resistance in which the charge current is diverted away from the voltage measurement point. Here, we report nonlocal spin-transport on two-dimensional surface-conducting SrTiO3 (STO) without a ferromagnetic spin-injector via the spin Hall effect (and inverse spin Hall effect). By applying magnetic fields to the Hall bars at different angles to the nonlocal spin-diffusion, we demonstrate an anisotropic spin-signal that is consistent with a Hanle precession of a pure spin current. We extract key transport parameters for surface-conducting STO, including: a spin Hall angle of γ ≈ (0.25 ± 0.05), a spin lifetime of τ ∼ 49 ps, and a spin diffusion length of λs ≈ (1.23 ± 0.7) μm at 2 K.
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Affiliation(s)
- Mi-Jin Jin
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Doo-Seung Um
- Department of Electrical Engineering, Sejong University, Seoul 05006, Republic of Korea
| | - Kohei Ohnishi
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
- Department of Physics, Kyushu University, 744 Motooka, Fukuoka 819-0395, Japan
| | - Sachio Komori
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Nadia Stelmashenko
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Daeseong Choe
- School of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Jung-Woo Yoo
- School of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Jason W A Robinson
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
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23
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Non-universal current flow near the metal-insulator transition in an oxide interface. Nat Commun 2021; 12:3311. [PMID: 34083533 PMCID: PMC8175561 DOI: 10.1038/s41467-021-23393-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 04/21/2021] [Indexed: 11/12/2022] Open
Abstract
In systems near phase transitions, macroscopic properties often follow algebraic scaling laws, determined by the dimensionality and the underlying symmetries of the system. The emergence of such universal scaling implies that microscopic details are irrelevant. Here, we locally investigate the scaling properties of the metal-insulator transition at the LaAlO3/SrTiO3 interface. We show that, by changing the dimensionality and the symmetries of the electronic system, coupling between structural and electronic properties prevents the universal behavior near the transition. By imaging the current flow in the system, we reveal that structural domain boundaries modify the filamentary flow close to the transition point, preventing a fractal with the expected universal dimension from forming. Macroscopic properties usually follow algebraic scaling laws near phase transitions. Here, the authors investigate the scaling properties of the metal‐insulator transition at the LaAlO3/SrTiO3 interface, finding that coupling between structural and electronic properties prevents the universal behavior.
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24
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Huang C, Fu J, Xiang M, Zhang J, Zeng H, Shao X. Single-Layer MoS 2 Grown on Atomically Flat SrTiO 3 Single Crystal for Enhanced Trionic Luminescence. ACS NANO 2021; 15:8610-8620. [PMID: 33949856 DOI: 10.1021/acsnano.1c00482] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The elaborate interface interactions can be critical in determining the achievable functionality of a semiconductor heterojunction (SH), particularly when two-dimensional material is enclosed in the system and its thickness is at an atomic extreme. In this work, we have successfully constructed a SH model system composed of typical transition-metal chalcogenide (TMDs) and transition metal oxides (TMO) by directly growing molybdenum sulfide (MoS2) nanosheets on atomically flat strontium titanate (SrTiO3) single crystal substrates through a conventional chemical vapor deposition (CVD) synthetic method. Multiple measurements have demonstrated the uniform monolayer thickness and single crystallinity of the MoS2 nanosheets as well as the atomic flatness of the heterojunction surface, both characterizing an extremely high quality of the interface. Clear evidence have been obtained for the electron transfer from the MoS2 adlayer to the SrTiO3 substrate which varies against the interface conditions. More importantly, the photoluminescence of MoS2 is significantly tailored, which is correlated with both the cleanness of the interface and the crystal orientation of the SrTiO3 substrate. These results not only shed fresh lights on the structure-property relationship of the TMDs/TMO heterostructures but also manifest the importance of the ideal interface structure for a hybridized system.
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25
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Maurel L, Herrero-Martín J, Motti F, Vasili HB, Piamonteze C, Heyderman LJ, Scagnoli V. Route to tunable room temperature electric polarization in SrTiO 3-CoFe 2O 4 heterostructures. JOURNAL OF MATERIALS CHEMISTRY. C 2021; 9:5977-5984. [PMID: 34094567 PMCID: PMC8118119 DOI: 10.1039/d0tc05821a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 04/13/2021] [Indexed: 06/12/2023]
Abstract
Utilizing the magnetostrictive properties of CoFe2O4, we demonstrate reversible room temperature control of the Ti electronic structure in SrTiO3-CoFe2O4 heterostructures, by inducing local and reversible strain in the SrTiO3. By means of X-ray absorption spectroscopy, we have ascertained the changes that take place in the energy levels of the Ti 3d orbitals under the influence of an external magnetic field. The observed Ti electronic state when the sample is subjected to moderately large external magnetic fields and the disappearance of the induced phase upon their removal indicates lattice distortions that are suggestive of the development of a net electric polarization.
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Affiliation(s)
- Laura Maurel
- Laboratory for Mesoscopic Systems, Department of Materials, ETH Zurich 8093 Zurich Switzerland
- Paul Scherrer Institute 5232 Villigen PSI Switzerland
| | | | - Federico Motti
- Laboratory for Mesoscopic Systems, Department of Materials, ETH Zurich 8093 Zurich Switzerland
- Paul Scherrer Institute 5232 Villigen PSI Switzerland
| | - Hari Babu Vasili
- ALBA Synchrotron Light Source 08290 Cerdanyola del Vallès Barcelona Spain
| | | | - Laura J Heyderman
- Laboratory for Mesoscopic Systems, Department of Materials, ETH Zurich 8093 Zurich Switzerland
- Paul Scherrer Institute 5232 Villigen PSI Switzerland
| | - Valerio Scagnoli
- Laboratory for Mesoscopic Systems, Department of Materials, ETH Zurich 8093 Zurich Switzerland
- Paul Scherrer Institute 5232 Villigen PSI Switzerland
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26
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Moss B, Wang Q, Butler KT, Grau-Crespo R, Selim S, Regoutz A, Hisatomi T, Godin R, Payne DJ, Kafizas A, Domen K, Steier L, Durrant JR. Linking in situ charge accumulation to electronic structure in doped SrTiO 3 reveals design principles for hydrogen-evolving photocatalysts. NATURE MATERIALS 2021; 20:511-517. [PMID: 33432143 DOI: 10.1038/s41563-020-00868-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Accepted: 11/03/2020] [Indexed: 05/14/2023]
Abstract
Recently, high solar-to-hydrogen efficiencies were demonstrated using La and Rh co-doped SrTiO3 (La,Rh:SrTiO3) incorporated into a low-cost and scalable Z-scheme device, known as a photocatalyst sheet. However, the unique properties that enable La,Rh:SrTiO3 to support this impressive performance are not fully understood. Combining in situ spectroelectrochemical measurements with density functional theory and photoelectron spectroscopy produces a depletion model of Rh:SrTiO3 and La,Rh:SrTiO3 photocatalyst sheets. This reveals remarkable properties, such as deep flatband potentials (+2 V versus the reversible hydrogen electrode) and a Rh oxidation state dependent reorganization of the electronic structure, involving the loss of a vacant Rh 4d mid-gap state. This reorganization enables Rh:SrTiO3 to be reduced by co-doping without compromising the p-type character. In situ time-resolved spectroscopies show that the electronic structure reorganization induced by Rh reduction controls the electron lifetime in photocatalyst sheets. In Rh:SrTiO3, enhanced lifetimes can only be obtained at negative applied potentials, where the complete Z-scheme operates inefficiently. La co-doping fixes Rh in the 3+ state, which results in long-lived photogenerated electrons even at very positive potentials (+1 V versus the reversible hydrogen electrode), in which both components of the complete device operate effectively. This understanding of the role of co-dopants provides a new insight into the design principles for water-splitting devices based on bandgap-engineered metal oxides.
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Affiliation(s)
- Benjamin Moss
- Department of Chemistry, Imperial College London, London, UK
- Centre for Processable Electronics, Imperial College London, London, UK
| | - Qian Wang
- Department of Chemical System Engineering, School of Engineering, The University of Tokyo, Tokyo, Japan
- Department of Chemistry, University of Cambridge, Cambridge, UK
| | - Keith T Butler
- SciML, Scientific Computing Division, Rutherford Appleton Laboratory, Harwell, UK
| | | | - Shababa Selim
- Department of Chemistry, Imperial College London, London, UK
- Centre for Processable Electronics, Imperial College London, London, UK
| | - Anna Regoutz
- Department of Chemistry, University College London, London, UK
| | - Takashi Hisatomi
- Research Initiative for Supra-Materials, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Nagano, Japan
| | - Robert Godin
- Department of Chemistry, Imperial College London, London, UK
- Department of Chemistry, University of British Columbia, Kelowna, British Columbia, Canada
| | - David J Payne
- Department of Materials, Imperial College London, London, UK
| | - Andreas Kafizas
- Department of Chemistry, Imperial College London, London, UK
- Grantham Institute, Imperial College London, London, UK
| | - Kazunari Domen
- Department of Chemistry, University of Reading, Reading, UK
- Office of University Professor, The University of Tokyo, Tokyo, Japan
| | - Ludmilla Steier
- Department of Chemistry, Imperial College London, London, UK.
| | - James R Durrant
- Department of Chemistry, Imperial College London, London, UK
- Centre for Processable Electronics, Imperial College London, London, UK
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27
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Dahm RT, Erlandsen R, Trier F, Sambri A, Gennaro ED, Guarino A, Stampfer L, Christensen DV, Granozio FM, Jespersen TS. Size-Controlled Spalling of LaAlO 3/SrTiO 3 Micromembranes. ACS APPLIED MATERIALS & INTERFACES 2021; 13:12341-12346. [PMID: 33661598 DOI: 10.1021/acsami.0c21612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The ability to form freestanding oxide membranes of nanoscale thickness is of great interest for enabling material functionality and for integrating oxides in flexible electronic and photonic technologies. Recently, a route has been demonstrated for forming conducting heterostructure membranes of LaAlO3 and SrTiO3, the canonical system for oxide electronics. In this route, the epitaxial growth of LaAlO3 on SrTiO3 resulted in a strained state that relaxed by producing freestanding membranes with random sizes and locations. Here, we extend the method to enable self-formed LaAlO3/SrTiO3 micromembranes with control over membrane position, their lateral sizes from 2 to 20 μm, and with controlled transfer to other substrates of choice. This method opens up the possibility to study and use the two-dimensional electron gas in LaAlO3/SrTiO3 membranes for advanced device concepts.
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Affiliation(s)
- Rasmus T Dahm
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
- Department of Energy Conversion and Storage, Technical University of Denmark, Fysikvej, Building 310, 2800 Kgs. Lyngby, Denmark
| | - Ricci Erlandsen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
- Department of Energy Conversion and Storage, Technical University of Denmark, Fysikvej, Building 310, 2800 Kgs. Lyngby, Denmark
| | - Felix Trier
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Alessia Sambri
- CNR-SPIN, Complesso Universitario di Monte S. Angelo, Via Cintia, 80126 Naples, Italy
| | - Emiliano Di Gennaro
- Dipartimento di Fisica "E. Pancini", Compl. Univ. di Monte S. Angelo, Università di Napoli "Federico II", Via Cintia, 80126 Napoli, Italy
| | - Anita Guarino
- Department of Physical Sciences and Technologies of Matter, CNR-DSFTM NFFA Trieste Area Science Park, Basovizza Strada Statale 14, 34149 Trieste, Italy
| | - Lukas Stampfer
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Dennis V Christensen
- Department of Energy Conversion and Storage, Technical University of Denmark, Fysikvej, Building 310, 2800 Kgs. Lyngby, Denmark
| | | | - Thomas S Jespersen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
- Department of Energy Conversion and Storage, Technical University of Denmark, Fysikvej, Building 310, 2800 Kgs. Lyngby, Denmark
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28
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Guo L, Yan Y, Xu R, Li J, Zeng C. Zero-Bias Conductance Peaks Effectively Tuned by Gating-Controlled Rashba Spin-Orbit Coupling. PHYSICAL REVIEW LETTERS 2021; 126:057701. [PMID: 33605741 DOI: 10.1103/physrevlett.126.057701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 07/27/2020] [Accepted: 12/23/2020] [Indexed: 06/12/2023]
Abstract
Zero-bias conductance peaks (ZBCPs) can manifest a number of notable physical phenomena and thus provide critical characteristics to the underlying electronic systems. Here, we report observations of pronounced ZBCPs in hybrid junctions composed of an oxide heterostructure LaAlO_{3}/SrTiO_{3} and an elemental superconductor Nb, where the two-dimensional electron system (2DES) at the LaAlO_{3}/SrTiO_{3} interface is known to accommodate gate-tunable Rashba spin-orbit coupling (SOC). Remarkably, the ZBCPs exhibit a domelike dependence on the gate voltage, which correlates strongly with the nonmonotonic gate dependence of the Rashba SOC in the 2DES. The origin of the observed ZBCPs can be attributed to the reflectionless tunneling effect of electrons that undergo phase-coherent multiple Andreev reflection, and their gate dependence can be explained by the enhanced quantum coherence time of electrons in the 2DES with increased momentum separation due to SOC. We further demonstrate theoretically that, in the presence of a substantial proximity effect, the Rashba SOC can directly enhance the overall Andreev conductance in the 2DES-barrier-superconductor junctions. These findings not only highlight nontrivial interplay between electron spin and superconductivity revealed by ZBCPs, but also set forward the study of superconducting hybrid structures by means of controllable SOC, which has significant implications in various research fronts from superconducting spintronics to topological superconductivity.
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Affiliation(s)
- Linhai Guo
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at the Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yuedong Yan
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at the Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Rongge Xu
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
- School of Science, Westlake University, Hangzhou, Zhejiang 310024, China
| | - Jian Li
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
- School of Science, Westlake University, Hangzhou, Zhejiang 310024, China
| | - Changgan Zeng
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at the Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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29
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Portugal GR, Teodoro Arantes J. 2DEG and 2DHG in NaTaO3 polar thin films: thickness and strain dependency. NANO EXPRESS 2021. [DOI: 10.1088/2632-959x/abe01d] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
Two-dimensional (2D) carrier gases in perovskite surfaces and interfaces have been intensely studied since their properties are attractive to many functional devices and applications. Here, we demonstrate through ab initio DFT calculations that surface 2D carries gases can be found in NaTaO3 ultrathin films. Furthermore, we show the thickness dependence of such phenomenon and how it can be tuned when biaxial in-plane strain is applied. Tensile does not alter the valence and conduction character of the films but promotes 2D electron and hole gases in the (TaO2)+ and (NaO)− surfaces, respectively. Because of the competition between surface and strain effects to deal with the cleavage-induced polarity, biaxial compression is able to generate 2D hole gases in the (TaO2)+ surface instead. Such carrier-type and layer switching are explained through changes in the electrostatic potential balancing along the [001] direction and (Na,Ta) cations displacements. The presented results concern not only nanoelectronics but also catalytic applications where modulating bandgap and valence/conduction states is desired.
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30
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Linker T, Tiwari S, Fukushima S, Kalia RK, Krishnamoorthy A, Nakano A, Nomura KI, Shimamura K, Shimojo F, Vashishta P. Optically Induced Three-Stage Picosecond Amorphization in Low-Temperature SrTiO 3. J Phys Chem Lett 2020; 11:9605-9612. [PMID: 33124829 DOI: 10.1021/acs.jpclett.0c02873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Photoexcitation can drastically modify potential energy surfaces of materials, allowing access to hidden phases. SrTiO3 (STO) is an ideal material for photoexcitation studies due to its prevalent use in nanostructured devices and its rich range of functionality-changing lattice motions. Recently, a hidden ferroelectric phase in STO was accessed through weak terahertz excitation of polarization-inducing phonon modes. In contrast, whereas strong laser excitation was shown to induce nanostructures on STO surfaces and control nanopolarization patterns in STO-based heterostructures, the dynamic pathways underlying these optically induced structural changes remain unknown. Here nonadiabatic quantum molecular dynamics reveals picosecond amorphization in photoexcited STO at temperatures as low as 10 K. The three-stage pathway involves photoinduced charge transfer and optical phonon activation followed by nonlinear charge and lattice dynamics that ultimately lead to amorphization. This atomistic understanding could guide not only rational laser nanostructuring of STO but also broader "quantum materials on demand" technologies.
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Affiliation(s)
- Thomas Linker
- Collaboratory for Advanced Computing and Simulations, University of Southern California, Los Angeles, California 90089-0242, United States
| | - Subodh Tiwari
- Collaboratory for Advanced Computing and Simulations, University of Southern California, Los Angeles, California 90089-0242, United States
| | - Shogo Fukushima
- Department of Physics, Kumamoto University, Kumamoto 860-8555, Japan
| | - Rajiv K Kalia
- Collaboratory for Advanced Computing and Simulations, University of Southern California, Los Angeles, California 90089-0242, United States
| | - Aravind Krishnamoorthy
- Collaboratory for Advanced Computing and Simulations, University of Southern California, Los Angeles, California 90089-0242, United States
| | - Aiichiro Nakano
- Collaboratory for Advanced Computing and Simulations, University of Southern California, Los Angeles, California 90089-0242, United States
| | - Ken-Ichi Nomura
- Collaboratory for Advanced Computing and Simulations, University of Southern California, Los Angeles, California 90089-0242, United States
| | - Kohei Shimamura
- Department of Physics, Kumamoto University, Kumamoto 860-8555, Japan
| | - Fuyuki Shimojo
- Department of Physics, Kumamoto University, Kumamoto 860-8555, Japan
| | - Priya Vashishta
- Collaboratory for Advanced Computing and Simulations, University of Southern California, Los Angeles, California 90089-0242, United States
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31
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Briggeman M, Li J, Huang M, Lee H, Lee JW, Eom K, Eom CB, Irvin P, Levy J. Engineered spin-orbit interactions in LaAlO 3/SrTiO 3-based 1D serpentine electron waveguides. SCIENCE ADVANCES 2020; 6:6/48/eaba6337. [PMID: 33239285 PMCID: PMC7688326 DOI: 10.1126/sciadv.aba6337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 10/09/2020] [Indexed: 06/11/2023]
Abstract
The quest to understand, design, and synthesize new forms of quantum matter guides much of contemporary research in condensed matter physics. One-dimensional (1D) electronic systems form the basis for some of the most interesting and exotic phases of quantum matter. Here, we describe a family of quasi-1D nanostructures, based on LaAlO3/SrTiO3 electron waveguides, in which a sinusoidal transverse spatial modulation is imposed. These devices display unique dispersive features in the subband spectra, namely, a sizeable shift (∼7 T) in the spin-dependent subband minima, and fractional conductance plateaus. The first property can be understood as an engineered spin-orbit interaction associated with the periodic acceleration of electrons as they undulate through the nanowire (ballistically), while the second property signifies the presence of enhanced electron-electron scattering in this system. The ability to engineer these interactions in quantum wires contributes to the tool set of a 1D solid-state quantum simulation platform.
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Affiliation(s)
- Megan Briggeman
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA 15260, USA
| | - Jianan Li
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA 15260, USA
| | - Mengchen Huang
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA 15260, USA
| | - Hyungwoo Lee
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jung-Woo Lee
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Kitae Eom
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Chang-Beom Eom
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Patrick Irvin
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA 15260, USA
| | - Jeremy Levy
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA.
- Pittsburgh Quantum Institute, Pittsburgh, PA 15260, USA
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32
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Sheridan E, Chen L, Li J, Guo Q, Hao S, Yu M, Eom KT, Lee H, Lee JW, Eom CB, Irvin P, Levy J. Gate-Tunable Optical Nonlinearities and Extinction in Graphene/LaAlO 3/SrTiO 3 Nanostructures. NANO LETTERS 2020; 20:6966-6973. [PMID: 32870015 DOI: 10.1021/acs.nanolett.0c01379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We explore the ultrafast optical response of graphene subjected to intense (∼106 V/cm) local (∼10 nm) electric fields. Nanoscale gating of graphene is achieved using a voltage-biased, SrTiO3-based conductive nanowire junction "written" directly under the graphene and isolated from it by an insulating ultrathin (<2 nm) LaAlO3 barrier. Upon illumination with ultrafast visible-to-near-infrared (VIS-NIR) light pulses, the local field from the nanojunction creates a strong gate-tunable second-order nonlinearity in the graphene and produces a substantial difference-frequency (DFG) and sum-frequency generation (SFG) response detected by the nanojunction. Spectrally sharp, gate-tunable extinction features (>99.9%) are observed in the VIS-NIR and SFG spectral ranges, in parameter regimes that are positively correlated with the enhanced nonlinear response. The observed graphene-light interaction and nonlinear response are of fundamental interest and open the way for future exploitation in graphene-based optical devices such as phase shifters, modulators, and nanoscale THz sources.
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Affiliation(s)
- Erin Sheridan
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Pittsburgh Quantum Institute, Pittsburgh, Pennsylvania 15260, United States
| | - Lu Chen
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Pittsburgh Quantum Institute, Pittsburgh, Pennsylvania 15260, United States
| | - Jianan Li
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Pittsburgh Quantum Institute, Pittsburgh, Pennsylvania 15260, United States
| | - Qing Guo
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Pittsburgh Quantum Institute, Pittsburgh, Pennsylvania 15260, United States
| | - Shan Hao
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Pittsburgh Quantum Institute, Pittsburgh, Pennsylvania 15260, United States
| | - Muqing Yu
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Pittsburgh Quantum Institute, Pittsburgh, Pennsylvania 15260, United States
| | - Ki-Tae Eom
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53076, United States
| | - Hyungwoo Lee
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53076, United States
| | - Jung-Woo Lee
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53076, United States
| | - Chang-Beom Eom
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53076, United States
| | - Patrick Irvin
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Pittsburgh Quantum Institute, Pittsburgh, Pennsylvania 15260, United States
| | - Jeremy Levy
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Pittsburgh Quantum Institute, Pittsburgh, Pennsylvania 15260, United States
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33
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Trushin M, Sarkar S, Mathew S, Goswami S, Sahoo P, Wang Y, Yang J, Li W, MacManus-Driscoll JL, Chhowalla M, Adam S, Venkatesan T. Evidence of Rotational Fröhlich Coupling in Polaronic Trions. PHYSICAL REVIEW LETTERS 2020; 125:086803. [PMID: 32909796 DOI: 10.1103/physrevlett.125.086803] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 07/30/2020] [Indexed: 06/11/2023]
Abstract
Electrons commonly couple through Fröhlich interactions with longitudinal optical phonons to form polarons. However, trions possess a finite angular momentum and should therefore couple instead to rotational optical phonons. This creates a polaronic trion whose binding energy is determined by the crystallographic orientation of the lattice. Here, we demonstrate theoretically within the Fröhlich approach and experimentally by photoluminescence emission that the bare trion binding energy (20 meV) is significantly enhanced by the phonons at the interface between the two-dimensional semiconductor MoS_{2} and the bulk transition metal oxide SrTiO_{3}. The low-temperature binding energy changes from 60 meV in [001]-oriented substrates to 90 meV for [111] orientation, as a result of the counterintuitive interplay between the rotational axis of the MoS_{2} trion and that of the SrTiO_{3} phonon mode.
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Affiliation(s)
- Maxim Trushin
- Centre for Advanced 2D Materials, National University of Singapore, Singapore 117546
| | - Soumya Sarkar
- NUSNNI NanoCore, National University of Singapore, Singapore 117411
| | - Sinu Mathew
- NUSNNI NanoCore, National University of Singapore, Singapore 117411
| | - Sreetosh Goswami
- NUSNNI NanoCore, National University of Singapore, Singapore 117411
| | - Prasana Sahoo
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, United Kingdom CB30FS
| | - Yan Wang
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, United Kingdom CB30FS
| | - Jieun Yang
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, United Kingdom CB30FS
| | - Weiwei Li
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, United Kingdom CB30FS
| | - Judith L MacManus-Driscoll
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, United Kingdom CB30FS
| | - Manish Chhowalla
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, United Kingdom CB30FS
| | - Shaffique Adam
- Centre for Advanced 2D Materials, National University of Singapore, Singapore 117546
- Department of Physics, National University of Singapore, Singapore, 117551
- Yale-NUS College, Singapore 138527
| | - T Venkatesan
- NUSNNI NanoCore, National University of Singapore, Singapore 117411
- Department of Physics, National University of Singapore, Singapore, 117551
- Department of Electrical and Computer Engineering and Materials Science and Engineering, National University of Singapore, Singapore 117583
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34
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Song D, Xue D, Zeng S, Li C, Venkatesan T, Ariando A, Pennycook SJ. Atomic Origin of Interface-Dependent Oxygen Migration by Electrochemical Gating at the LaAlO 3-SrTiO 3 Heterointerface. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:2000729. [PMID: 32775157 PMCID: PMC7404156 DOI: 10.1002/advs.202000729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 05/30/2020] [Indexed: 06/11/2023]
Abstract
Electrical control of material properties based on ionic liquids (IL) has seen great development and emerging applications in the field of functional oxides, mainly understood by the electrostatic and electrochemical gating mechanisms. Compared to the fast, flexible, and reproducible electrostatic gating, electrochemical gating is less controllable owing to the complex behaviors of ion migration. Here, the interface-dependent oxygen migration by electrochemical gating is resolved at the atomic scale in the LaAlO3-SrTiO3 system through ex situ IL gating experiments and on-site atomic-resolution characterization. The difference between interface structures leads to the controllable electrochemical oxygen migration by filling oxygen vacancies. The findings not only provide an atomic-scale insight into the origin of interface-dependent electrochemical gating but also demonstrate an effective way of engineering interface structure to control the electrochemical gating.
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Affiliation(s)
- Dongsheng Song
- Department of Materials Science and EngineeringNational University of SingaporeSingapore117575Singapore
- NUSNNI‐NanocoreNational University of SingaporeSingapore117411Singapore
| | - Deqing Xue
- Department of Materials Science and EngineeringNational University of SingaporeSingapore117575Singapore
| | - Shengwei Zeng
- NUSNNI‐NanocoreNational University of SingaporeSingapore117411Singapore
- Department of PhysicsNational University of SingaporeSingapore117542Singapore
| | - Changjian Li
- Department of Materials Science and EngineeringNational University of SingaporeSingapore117575Singapore
- NUSNNI‐NanocoreNational University of SingaporeSingapore117411Singapore
| | - Thirumalai Venkatesan
- Department of Materials Science and EngineeringNational University of SingaporeSingapore117575Singapore
- NUSNNI‐NanocoreNational University of SingaporeSingapore117411Singapore
- Department of PhysicsNational University of SingaporeSingapore117542Singapore
| | - Ariando Ariando
- NUSNNI‐NanocoreNational University of SingaporeSingapore117411Singapore
- Department of PhysicsNational University of SingaporeSingapore117542Singapore
| | - Stephen J. Pennycook
- Department of Materials Science and EngineeringNational University of SingaporeSingapore117575Singapore
- NUSNNI‐NanocoreNational University of SingaporeSingapore117411Singapore
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35
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Murray C, van Efferen C, Jolie W, Fischer JA, Hall J, Rosch A, Krasheninnikov AV, Komsa HP, Michely T. Band Bending and Valence Band Quantization at Line Defects in MoS 2. ACS NANO 2020; 14:9176-9187. [PMID: 32602698 DOI: 10.1021/acsnano.0c04945] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The variation of the electronic structure normal to 1D defects in quasi-freestanding MoS2, grown by molecular beam epitaxy, is investigated through high resolution scanning tunneling spectroscopy at 5 K. Strong upward bending of valence and conduction bands toward the line defects is found for the 4|4E mirror twin boundary and island edges but not for the 4|4P mirror twin boundary. Quantized energy levels in the valence band are observed wherever upward band bending takes place. Focusing on the common 4|4E mirror twin boundary, density functional theory calculations give an estimate of its charging, which agrees well with electrostatic modeling. We show that the line charge can also be assessed from the filling of the boundary-localized electronic band, whereby we provide a measurement of the theoretically predicted quantized polarization charge at MoS2 mirror twin boundaries. These calculations elucidate the origin of band bending and charging at these 1D defects in MoS2. The 4|4E mirror twin boundary not only impairs charge transport of electrons and holes due to band bending, but holes are additionally subject to a potential barrier, which is inferred from the independence of the quantized energy landscape on either side of the boundary.
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Affiliation(s)
- Clifford Murray
- II. Physikalisches Institut, Universität zu Köln, Cologne D-50937, Germany
| | - Camiel van Efferen
- II. Physikalisches Institut, Universität zu Köln, Cologne D-50937, Germany
| | - Wouter Jolie
- II. Physikalisches Institut, Universität zu Köln, Cologne D-50937, Germany
- Institut für Materialphysik, Westfälische Wilhelms-Universität Münster, Münster D-48149, Germany
| | | | - Joshua Hall
- II. Physikalisches Institut, Universität zu Köln, Cologne D-50937, Germany
| | - Achim Rosch
- Institut für Theoretische Physik, Universität zu Köln, Cologne D-50937, Germany
| | - Arkady V Krasheninnikov
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden D-01328, Germany
- Department of Applied Physics, Aalto University School of Science, Aalto FI-00076, Finland
| | - Hannu-Pekka Komsa
- Department of Applied Physics, Aalto University School of Science, Aalto FI-00076, Finland
- Microelectronics Research Unit, University of Oulu, Oulu FI-90014, Finland
| | - Thomas Michely
- II. Physikalisches Institut, Universität zu Köln, Cologne D-50937, Germany
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36
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Shi XL, Zou J, Chen ZG. Advanced Thermoelectric Design: From Materials and Structures to Devices. Chem Rev 2020; 120:7399-7515. [PMID: 32614171 DOI: 10.1021/acs.chemrev.0c00026] [Citation(s) in RCA: 359] [Impact Index Per Article: 89.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The long-standing popularity of thermoelectric materials has contributed to the creation of various thermoelectric devices and stimulated the development of strategies to improve their thermoelectric performance. In this review, we aim to comprehensively summarize the state-of-the-art strategies for the realization of high-performance thermoelectric materials and devices by establishing the links between synthesis, structural characteristics, properties, underlying chemistry and physics, including structural design (point defects, dislocations, interfaces, inclusions, and pores), multidimensional design (quantum dots/wires, nanoparticles, nanowires, nano- or microbelts, few-layered nanosheets, nano- or microplates, thin films, single crystals, and polycrystalline bulks), and advanced device design (thermoelectric modules, miniature generators and coolers, and flexible thermoelectric generators). The outline of each strategy starts with a concise presentation of their fundamentals and carefully selected examples. In the end, we point out the controversies, challenges, and outlooks toward the future development of thermoelectric materials and devices. Overall, this review will serve to help materials scientists, chemists, and physicists, particularly students and young researchers, in selecting suitable strategies for the improvement of thermoelectrics and potentially other relevant energy conversion technologies.
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Affiliation(s)
- Xiao-Lei Shi
- Centre for Future Materials, University of Southern Queensland, Springfield Central, Queensland 4300, Australia.,School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Jin Zou
- School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia.,Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Zhi-Gang Chen
- Centre for Future Materials, University of Southern Queensland, Springfield Central, Queensland 4300, Australia.,School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia
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37
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Strain-induced room-temperature ferroelectricity in SrTiO 3 membranes. Nat Commun 2020; 11:3141. [PMID: 32561835 PMCID: PMC7305178 DOI: 10.1038/s41467-020-16912-3] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 05/30/2020] [Indexed: 11/09/2022] Open
Abstract
Advances in complex oxide heteroepitaxy have highlighted the enormous potential of utilizing strain engineering via lattice mismatch to control ferroelectricity in thin-film heterostructures. This approach, however, lacks the ability to produce large and continuously variable strain states, thus limiting the potential for designing and tuning the desired properties of ferroelectric films. Here, we observe and explore dynamic strain-induced ferroelectricity in SrTiO3 by laminating freestanding oxide films onto a stretchable polymer substrate. Using a combination of scanning probe microscopy, optical second harmonic generation measurements, and atomistic modeling, we demonstrate robust room-temperature ferroelectricity in SrTiO3 with 2.0% uniaxial tensile strain, corroborated by the notable features of 180° ferroelectric domains and an extrapolated transition temperature of 400 K. Our work reveals the enormous potential of employing oxide membranes to create and enhance ferroelectricity in environmentally benign lead-free oxides, which hold great promise for applications ranging from non-volatile memories and microwave electronics. Previous approach lacks the ability to produce large and continuously tunable strain states due to the limited number of available substrates. Here, the authors demonstrate strain-induced ferroelectricity in SrTiO3 membranes by laminating freestanding SrTiO3 films onto a stretchable polymer.
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38
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Strain modulation of TaO 4 planarity in tantalates ultrathin films: surface states engineering. Sci Rep 2020; 10:7828. [PMID: 32385285 PMCID: PMC7210982 DOI: 10.1038/s41598-020-64315-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 04/06/2020] [Indexed: 11/08/2022] Open
Abstract
Ultrathin films of perovskites have attracted considerable attention once they fit in numerous applications. Over the years, controlling and tuning their properties have been attainable when biaxial strain is applied. Through ab initio DFT calculations, (110) ultrathin (Na,K)TaO3 films were submitted to biaxial tensile and compressive strain. Intrinsically, surface Ta shallow states emerge into the bandgap since the (110) cleavage breaks its octahedral symmetry to create TaO4 units. Removal of ligands along the x-y plane stabilizes dx2-y2 orbitals, which decrease in energy due to lower electrostatic repulsion. Such stabilization is maximized when biaxial tensile increases the TaO4 planarity towards a square planar symmetry. Accordingly, the corresponding electronic levels move further into the bandgap. Conversely, compressive biaxial strain intensifies electrostatic repulsion, closing the TaO4 tetrahedra, and surface states move to higher energy zones. The reported strain-driven modulation might be applied in different applications, as photocatalysis, ferroelectricity, and spintronics.
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39
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Zhou Y, Wang W, Zhang C, Huang D, Lai C, Cheng M, Qin L, Yang Y, Zhou C, Li B, Luo H, He D. Sustainable hydrogen production by molybdenum carbide-based efficient photocatalysts: From properties to mechanism. Adv Colloid Interface Sci 2020; 279:102144. [PMID: 32222608 DOI: 10.1016/j.cis.2020.102144] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 03/13/2020] [Accepted: 03/17/2020] [Indexed: 12/28/2022]
Abstract
Hydrogen is considered to be a promising energy carrier to solve the issue of energy crisis. Molybdenum carbide (MoxC) is the typical material, which has similar properties of Pt and thought to be an attractive alternative to noble metals for H2 evolution. The study of MoxC as alternative catalyst for H2 production is almost focused on electrocatalytic field, while the application of MoxC as a co-catalyst in photocatalytic H2 evolution has received in-depth research in recent years. Particularly, MoxC exhibits significant enhancement in the H2 production performance of semiconductors under visible light irradiation. However, a review discussing MoxC serving as a co-catalysts in the photocatalytic H2 evolution is still absent. Herein, the recent progress of MoxC on photocatalytic H2 evolution is reviewed. Firstly, the preparation methods including chemical vapor deposition, temperature programming, and organic-inorganic hybridization are detailly summarized. Then, the fundamental structure, electronic properties, and specific conductance of MoxC are illustrated to illuminate the advantages of MoxC as a co-catalyst for H2 evolution. Furthermore, the different heterojunctions formed between MoxC and other semiconductors for enhancing the photocatalytic performance are emphasized. Finally, perspectives regarding the current challenges and the future research directions on the improvement of catalytic performance of MoxC-based photocatalysts are also presented.
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Affiliation(s)
- Yin Zhou
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Wenjun Wang
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Chen Zhang
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China.
| | - Danlian Huang
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China.
| | - Cui Lai
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Min Cheng
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Lei Qin
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Yang Yang
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Chengyun Zhou
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Bisheng Li
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Hanzhuo Luo
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Donghui He
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
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40
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Bao Z, Fung V, Polo-Garzon F, Hood ZD, Cao S, Chi M, Bai L, Jiang DE, Wu Z. The interplay between surface facet and reconstruction on isopropanol conversion over SrTiO3 nanocrystals. J Catal 2020. [DOI: 10.1016/j.jcat.2020.02.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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41
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Li X, Qiu T, Zhang J, Baldini E, Lu J, Rappe AM, Nelson KA. Terahertz field-induced ferroelectricity in quantum paraelectric SrTiO 3. Science 2020; 364:1079-1082. [PMID: 31197011 DOI: 10.1126/science.aaw4913] [Citation(s) in RCA: 114] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 05/20/2019] [Indexed: 11/02/2022]
Abstract
"Hidden phases" are metastable collective states of matter that are typically not accessible on equilibrium phase diagrams. These phases can host exotic properties in otherwise conventional materials and hence may enable novel functionality and applications, but their discovery and access are still in early stages. Using intense terahertz electric field excitation, we found that an ultrafast phase transition into a hidden ferroelectric phase can be dynamically induced in quantum paraelectric strontium titanate (SrTiO3). The induced lowering in crystal symmetry yields substantial changes in the phonon excitation spectra. Our results demonstrate collective coherent control over material structure, in which a single-cycle field drives ions along the microscopic pathway leading directly to their locations in a new crystalline phase on an ultrafast time scale.
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Affiliation(s)
- Xian Li
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Tian Qiu
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jiahao Zhang
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Edoardo Baldini
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jian Lu
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Andrew M Rappe
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Keith A Nelson
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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42
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Daelman N, Hegner FS, Rellán-Piñeiro M, Capdevila-Cortada M, García-Muelas R, López N. Quasi-degenerate states and their dynamics in oxygen deficient reducible metal oxides. J Chem Phys 2020; 152:050901. [PMID: 32035446 DOI: 10.1063/1.5138484] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The physical and chemical properties of oxides are defined by the presence of oxygen vacancies. Experimentally, non-defective structures are almost impossible to achieve due to synthetic constraints. Therefore, it is crucial to account for vacancies when evaluating the characteristics of these materials. The electronic structure of oxygen-depleted oxides deeply differs from that of the native forms, in particular, of reducible metal oxides, where excess electrons can localize in various distinct positions. In this perspective, we present recent developments from our group describing the complexity of these defective materials that highlight the need for an accurate description of (i) intrinsic vacancies in polar terminations, (ii) multiple geometries and complex electronic structures with several states attainable at typical working conditions, and (iii) the associated dynamics for both vacancy diffusion and the coexistence of more than one electronic structure. All these aspects widen our current understanding of defects in oxides and need to be adequately introduced in emerging high-throughput screening methodologies.
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Affiliation(s)
- Nathan Daelman
- Institute of Chemical Research of Catalonia, ICIQ, The Barcelona Institute of Science and Technology, BIST, Av. Països Catalans 16, 43007 Tarragona, Spain
| | - Franziska Simone Hegner
- Institute of Chemical Research of Catalonia, ICIQ, The Barcelona Institute of Science and Technology, BIST, Av. Països Catalans 16, 43007 Tarragona, Spain
| | - Marcos Rellán-Piñeiro
- Institute of Chemical Research of Catalonia, ICIQ, The Barcelona Institute of Science and Technology, BIST, Av. Països Catalans 16, 43007 Tarragona, Spain
| | - Marçal Capdevila-Cortada
- Institute of Chemical Research of Catalonia, ICIQ, The Barcelona Institute of Science and Technology, BIST, Av. Països Catalans 16, 43007 Tarragona, Spain
| | - Rodrigo García-Muelas
- Institute of Chemical Research of Catalonia, ICIQ, The Barcelona Institute of Science and Technology, BIST, Av. Països Catalans 16, 43007 Tarragona, Spain
| | - Núria López
- Institute of Chemical Research of Catalonia, ICIQ, The Barcelona Institute of Science and Technology, BIST, Av. Països Catalans 16, 43007 Tarragona, Spain
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43
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Pulikkotil JJ. A spin-orbit coupling-induced two-dimensional electron gas in BiAlO 3/SrTiO 3 heterostructures. Phys Chem Chem Phys 2020; 22:3122-3127. [PMID: 31967128 DOI: 10.1039/c9cp05737d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Both LaAlO3 and BiAlO3 are isostructural, isoelectronic and band insulators. Therefore, in analogy to the LaAlO3/SrTiO3 heterostructure, a quasi two dimensional electron gas (q-2DEG) could be anticipated in BiAlO3/SrTiO3 heterostructures. Our density functional theory based scalar relativistic calculations show that BiAlO3/SrTiO3 heterostructures remain insulating for a BiAlO3 film thickness up to 5 unit cells. However, with spin orbit coupling included in the crystal Hamiltonian, we find a thickness dependent insulator to metal transition for BiAlO3/SrTiO3 heterostructures. However, unlike the Ti3+/Ti4+ electronic reconstruction in LaAlO3/SrTiO3, the conductivity in BiAlO3/SrTiO3 is found to originate from the subsurface Bi 6p states. The results suggest that the properties of q-2DEG in BiAlO3/SrTiO3 can be controlled using an external electric field, leading to a wide range of solid state applications.
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Affiliation(s)
- J J Pulikkotil
- CSIR-National Physical Laboratory, Dr K. S. Krishnan Marg, New Delhi 110012, India.
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44
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Synthesis, characterization and in vitro biocompatibility study of strontium titanate ceramic: A potential biomaterial. J Mech Behav Biomed Mater 2020; 102:103494. [DOI: 10.1016/j.jmbbm.2019.103494] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 10/13/2019] [Accepted: 10/13/2019] [Indexed: 12/20/2022]
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45
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Santana JA, Krogel JT, Okamoto S, Reboredo FA. Electron Confinement and Magnetism of (LaTiO3)1/(SrTiO3)5 Heterostructure: A Diffusion Quantum Monte Carlo Study. J Chem Theory Comput 2019; 16:643-650. [DOI: 10.1021/acs.jctc.9b00678] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Juan A. Santana
- Department of Chemistry, University of Puerto Rico at Cayey, P.O. Box 372230, Cayey, PR 00737-2230, United States
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Jaron T. Krogel
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Satoshi Okamoto
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Fernando A. Reboredo
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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46
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Choe D, Jin MJ, Kim SI, Choi HJ, Jo J, Oh I, Park J, Jin H, Koo HC, Min BC, Hong S, Lee HW, Baek SH, Yoo JW. Gate-tunable giant nonreciprocal charge transport in noncentrosymmetric oxide interfaces. Nat Commun 2019; 10:4510. [PMID: 31586096 PMCID: PMC6778138 DOI: 10.1038/s41467-019-12466-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 09/06/2019] [Indexed: 11/09/2022] Open
Abstract
A polar conductor, where inversion symmetry is broken, may exhibit directional propagation of itinerant electrons, i.e., the rightward and leftward currents differ from each other, when time-reversal symmetry is also broken. This potential rectification effect was shown to be very weak due to the fact that the kinetic energy is much higher than the energies associated with symmetry breaking, producing weak perturbations. Here we demonstrate the appearance of giant nonreciprocal charge transport in the conductive oxide interface, LaAlO3/SrTiO3, where the electrons are confined to two-dimensions with low Fermi energy. In addition, the Rashba spin-orbit interaction correlated with the sub-band hierarchy of this system enables a strongly tunable nonreciprocal response by applying a gate voltage. The observed behavior of directional response in LaAlO3/SrTiO3 is associated with comparable energy scales among kinetic energy, spin-orbit interaction, and magnetic field, which inspires a promising route to enhance nonreciprocal response and its functionalities in spin orbitronics.
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Affiliation(s)
- Daeseong Choe
- School of Materials Science and Engineering-Low Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology, Ulsan, 44919, Korea
| | - Mi-Jin Jin
- School of Materials Science and Engineering-Low Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology, Ulsan, 44919, Korea
| | - Shin-Ik Kim
- Center for Electronic Materials, Korea Institute of Science and Technology, Seoul, 02792, Korea
| | - Hyung-Jin Choi
- Center for Electronic Materials, Korea Institute of Science and Technology, Seoul, 02792, Korea
| | - Junhyeon Jo
- School of Materials Science and Engineering-Low Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology, Ulsan, 44919, Korea
| | - Inseon Oh
- School of Materials Science and Engineering-Low Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology, Ulsan, 44919, Korea
| | - Jungmin Park
- School of Materials Science and Engineering-Low Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology, Ulsan, 44919, Korea.,Center for Scientific Instrumentation, Division of Scientific Instrumentation & Management, Korea Basic Science Institute, Daejeon, 305-806, Korea
| | - Hosub Jin
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan, 44919, Korea
| | - Hyun Cheol Koo
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Korea.,KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, 02841, Korea
| | - Byoung-Chul Min
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Korea.,Division of Nano and Information Technology, KIST School, Korea University of Science and Technology, Seoul, 02792, Korea
| | - Seokmin Hong
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Korea
| | - Hyun-Woo Lee
- Department of Physics, Pohang University of Science and Technology, Pohang, 37673, Korea
| | - Seung-Hyub Baek
- Center for Electronic Materials, Korea Institute of Science and Technology, Seoul, 02792, Korea.,Division of Nano and Information Technology, KIST School, Korea University of Science and Technology, Seoul, 02792, Korea
| | - Jung-Woo Yoo
- School of Materials Science and Engineering-Low Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology, Ulsan, 44919, Korea.
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47
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Bhansali S, Khunsin W, Chatterjee A, Santiso J, Abad B, Martin-Gonzalez M, Jakob G, Sotomayor Torres CM, Chávez-Angel E. Enhanced thermoelectric properties of lightly Nb doped SrTiO 3 thin films. NANOSCALE ADVANCES 2019; 1:3647-3653. [PMID: 36133557 PMCID: PMC9419777 DOI: 10.1039/c9na00361d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 07/30/2019] [Indexed: 06/16/2023]
Abstract
Novel thermoelectric materials developed for operation at room temperature must have similar or better performance along with being as ecofriendly as those commercially used, e.g., Bi2Te3, in terms of their toxicity and cost. In this work, we present an in-depth study of the thermoelectric properties of epitaxial Nb-doped strontium titanate (SrTi1-x Nb x O3) thin films as a function of (i) doping concentration, (ii) film thickness and (iii) substrate type. The excellent crystal quality was confirmed by high resolution transmission electron microscopy and X-ray diffraction analysis. The thermoelectric properties were measured by the three-omega method (thermal conductivity) and van der Pauw method (electrical resistivity), complemented by Seebeck coefficient measurements. A maximum power factor of 8.9 × 10-3 W m-1 K-2 and a thermoelectric figure of merit of 0.49 were measured at room temperature in 50 nm-thick films grown on lanthanum strontium aluminate. The mechanisms behind this high figure of merit are discussed in terms of a possible two-dimensional electron gas, increase of the effective mass of the electrons, electron filtering and change in strain due to different substrates. The overall enhancement of the thermoelectric properties suggests that SrTi1-x Nb x O3 is a very promising n-type candidate for room- to high-temperature applications.
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Affiliation(s)
- S Bhansali
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC, The Barcelona Institute of Science and Technology Campus UAB, Bellaterra 08193 Barcelona Spain
| | - W Khunsin
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC, The Barcelona Institute of Science and Technology Campus UAB, Bellaterra 08193 Barcelona Spain
| | - A Chatterjee
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC, The Barcelona Institute of Science and Technology Campus UAB, Bellaterra 08193 Barcelona Spain
| | - J Santiso
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC, The Barcelona Institute of Science and Technology Campus UAB, Bellaterra 08193 Barcelona Spain
| | - B Abad
- Instituto de Microelectronica de Madrid, IMM-CNM, CSIC Isaac Newton, 8 PTM 28760 Tres Cantos (Madrid) Spain
| | - M Martin-Gonzalez
- Instituto de Microelectronica de Madrid, IMM-CNM, CSIC Isaac Newton, 8 PTM 28760 Tres Cantos (Madrid) Spain
| | - G Jakob
- Institut für Physik, Johannes Gutenberg Universität Mainz Staudingerweg 7 55128 Mainz Germany
- Graduate School Materials Science in Mainz Staudingerweg 9 55128 Mainz Germany
| | - C M Sotomayor Torres
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC, The Barcelona Institute of Science and Technology Campus UAB, Bellaterra 08193 Barcelona Spain
- ICREA Passeig Lluis Companys 23 08010 Barcelona Spain
| | - E Chávez-Angel
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC, The Barcelona Institute of Science and Technology Campus UAB, Bellaterra 08193 Barcelona Spain
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48
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Luo W, Boselli M, Poumirol JM, Ardizzone I, Teyssier J, van der Marel D, Gariglio S, Triscone JM, Kuzmenko AB. High sensitivity variable-temperature infrared nanoscopy of conducting oxide interfaces. Nat Commun 2019; 10:2774. [PMID: 31235858 PMCID: PMC6591405 DOI: 10.1038/s41467-019-10672-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 05/21/2019] [Indexed: 11/09/2022] Open
Abstract
Probing the local transport properties of two-dimensional electron systems (2DES) confined at buried interfaces requires a non-invasive technique with a high spatial resolution operating in a broad temperature range. In this paper, we investigate the scattering-type scanning near field optical microscopy as a tool for studying the conducting LaAlO3/SrTiO3 interface from room temperature down to 6 K. We show that the near-field optical signal, in particular its phase component, is highly sensitive to the transport properties of the electron system present at the interface. Our modeling reveals that such sensitivity originates from the interaction of the AFM tip with coupled plasmon-phonon modes with a small penetration depth. The model allows us to quantitatively correlate changes in the optical signal with the variation of the 2DES transport properties induced by cooling and by electrostatic gating. To probe the spatial resolution of the technique, we image conducting nano-channels written in insulating heterostructures with a voltage-biased tip of an atomic force microscope.
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Affiliation(s)
- Weiwei Luo
- Department of Quantum Matter Physics, University of Geneva, Quai Ernest-Ansermet 24, 1211, Geneva, Switzerland
| | - Margherita Boselli
- Department of Quantum Matter Physics, University of Geneva, Quai Ernest-Ansermet 24, 1211, Geneva, Switzerland
| | - Jean-Marie Poumirol
- Department of Quantum Matter Physics, University of Geneva, Quai Ernest-Ansermet 24, 1211, Geneva, Switzerland
| | - Ivan Ardizzone
- Department of Quantum Matter Physics, University of Geneva, Quai Ernest-Ansermet 24, 1211, Geneva, Switzerland
| | - Jérémie Teyssier
- Department of Quantum Matter Physics, University of Geneva, Quai Ernest-Ansermet 24, 1211, Geneva, Switzerland
| | - Dirk van der Marel
- Department of Quantum Matter Physics, University of Geneva, Quai Ernest-Ansermet 24, 1211, Geneva, Switzerland
| | - Stefano Gariglio
- Department of Quantum Matter Physics, University of Geneva, Quai Ernest-Ansermet 24, 1211, Geneva, Switzerland
| | - Jean-Marc Triscone
- Department of Quantum Matter Physics, University of Geneva, Quai Ernest-Ansermet 24, 1211, Geneva, Switzerland
| | - Alexey B Kuzmenko
- Department of Quantum Matter Physics, University of Geneva, Quai Ernest-Ansermet 24, 1211, Geneva, Switzerland.
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49
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Rodenbücher C, Menzel S, Wrana D, Gensch T, Korte C, Krok F, Szot K. Current channeling along extended defects during electroreduction of SrTiO 3. Sci Rep 2019; 9:2502. [PMID: 30792458 PMCID: PMC6385180 DOI: 10.1038/s41598-019-39372-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 01/23/2019] [Indexed: 11/09/2022] Open
Abstract
Electroreduction experiments on metal oxides are well established for investigating the nature of the material change in memresistive devices, whose basic working principle is an electrically-induced reduction. While numerous research studies on this topic have been conducted, the influence of extended defects such as dislocations has not been addressed in detail hitherto. Here, we show by employing thermal microscopy to detect local Joule heating effects in the first stage of electroreduction of SrTiO3 that the current is channelled along extended defects such as dislocations which were introduced mechanically by scratching or sawing. After prolonged degradation, the matrix of the crystal is also electroreduced and the influence of the initially present dislocations diminished. At this stage, a hotspot at the anode develops due to stoichiometry polarisation leading not only to the gliding of existing dislocations, but also to the evolution of new dislocations. Such a formation is caused by electrical and thermal stress showing dislocations may play a significant role in resistive switching effects.
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Affiliation(s)
- Christian Rodenbücher
- Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research (IEK-3), 52425, Jülich, Germany.
| | - Stephan Menzel
- Forschungszentrum Jülich GmbH, Peter Grünberg Institute (PGI-7), 52425, Jülich, Germany
- Forschungszentrum Jülich GmbH, JARA-FIT, 52425, Jülich, Germany
| | - Dominik Wrana
- Forschungszentrum Jülich GmbH, Peter Grünberg Institute (PGI-7), 52425, Jülich, Germany
- Forschungszentrum Jülich GmbH, JARA-FIT, 52425, Jülich, Germany
- Jagiellonian University, Marian Smoluchowski Institute of Physics, 30-348, Krakow, Poland
| | - Thomas Gensch
- Forschungszentrum Jülich GmbH, Institute of Complex Systems (ICS-4), 52425, Jülich, Germany
| | - Carsten Korte
- Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research (IEK-3), 52425, Jülich, Germany
| | - Franciszek Krok
- Jagiellonian University, Marian Smoluchowski Institute of Physics, 30-348, Krakow, Poland
| | - Krzysztof Szot
- Forschungszentrum Jülich GmbH, Peter Grünberg Institute (PGI-7), 52425, Jülich, Germany
- Forschungszentrum Jülich GmbH, JARA-FIT, 52425, Jülich, Germany
- University of Silesia, A. Chełkowski Institute of Physics, 40-007, Katowice, Poland
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50
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Huang Z, Renshaw Wang X, Rusydi A, Chen J, Yang H, Venkatesan T. Interface Engineering and Emergent Phenomena in Oxide Heterostructures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1802439. [PMID: 30133012 DOI: 10.1002/adma.201802439] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 07/06/2018] [Indexed: 06/08/2023]
Abstract
Complex oxide interfaces have mesmerized the scientific community in the last decade due to the possibility of creating tunable novel multifunctionalities, which are possible owing to the strong interaction among charge, spin, orbital, and structural degrees of freedom. Artificial interfacial modifications, which include defects, formal polarization, structural symmetry breaking, and interlayer interaction, have led to novel properties in various complex oxide heterostructures. These emergent phenomena not only serve as a platform for investigating strong electronic correlations in low-dimensional systems but also provide potentials for exploring next-generation electronic devices with high functionality. Herein, some recently developed strategies in engineering functional oxide interfaces and their emergent properties are reviewed.
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Affiliation(s)
- Zhen Huang
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Xiao Renshaw Wang
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Andrivo Rusydi
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Jingsheng Chen
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Hyunsoo Yang
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Thirumalai Venkatesan
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
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