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Köksal O, Li LL, Pentcheva R. High Chern numbers in a perovskite-derived dice lattice (LaXO 3) 3/(LaAlO 3) 3(111) with X = Ti, Mn and Co. Sci Rep 2023; 13:10615. [PMID: 37391462 DOI: 10.1038/s41598-023-36170-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 05/30/2023] [Indexed: 07/02/2023] Open
Abstract
The dice lattice, containing a stack of three triangular lattices, has been proposed to exhibit nontrivial flat bands with nonzero Chern numbers, but unlike the honeycomb lattice it is much less studied. By employing density-functional theory (DFT) calculations with an on-site Coulomb repulsion term, we explore systematically the electronic and topological properties of (LaXO3)3/(LaAlO3)3(111) superlattices with X = Ti, Mn and Co, where a LaAlO3 trilayer spacer confines the LaXO3 (LXO) dice lattice. In the absence of spin-orbit coupling (SOC) with symmetry constrained to P3, the ferromagnetic (FM) phase of the LXO(111) trilayers exhibits a half-metallic band structure with multiple Dirac crossings and coupled electron-hole pockets around the Fermi energy. Symmetry lowering induces a significant rearrangement of bands and triggers a metal-to-insulator transition. Inclusion of SOC leads to a substantial anomalous Hall conductivity (AHC) around the Fermi energy reaching values up to [Formula: see text] for X = Mn and Co in P3 symmetry and both in- and out-of-plane magnetization directions in the first case and along [001] in the latter. The dice lattice emerges as a promising playground to realise nontrivial topological phases with high Chern numbers.
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Affiliation(s)
- Okan Köksal
- Department of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Lotharstr. 1, 47057, Duisburg, Germany
| | - L L Li
- Department of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Lotharstr. 1, 47057, Duisburg, Germany
| | - Rossitza Pentcheva
- Department of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Lotharstr. 1, 47057, Duisburg, Germany.
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2
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Bhattacharya S, Datta S. Evidence of linear and cubic Rashba effect in non-magnetic heterostructure. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:205501. [PMID: 36848680 DOI: 10.1088/1361-648x/acbf94] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 02/27/2023] [Indexed: 06/18/2023]
Abstract
TheLaAlO3/KTaO3system serves as a prototype to study the electronic properties that emerge as a result of spin-orbit coupling (SOC). In this article, we have used first-principles calculations to systematically study two types of defect-free (0 0 1) interfaces, which are termed as Type-I and Type-II. While the Type-I heterostructure produces a two dimensional (2D) electron gas, the Type-II heterostructure hosts an oxygen-rich 2D hole gas at the interface. Furthermore, in the presence of intrinsic SOC, we have found evidence of both cubic and linear Rashba interactions in the conduction bands of the Type-I heterostructure. On the contrary, there is spin-splitting of both the valence and the conduction bands in the Type-II interface, which are found to be only linear Rashba type. Interestingly, the Type-II interface also harbors a potential photocurrent transition path, making it an excellent platform to study the circularly polarized photogalvanic effect.
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Affiliation(s)
- Sanchari Bhattacharya
- Department of Physics and Astronomy, National Institute of Technology, Rourkela, 769008 Odisha, India
| | - Sanjoy Datta
- Department of Physics and Astronomy, National Institute of Technology, Rourkela, 769008 Odisha, India
- Center for Nanomaterials, National Institute of Technology, Rourkela, 769008 Odisha, India
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3
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Burzo E, Tetean R. New Insights on the Spin Glass Behavior in Ferrites Nanoparticles. NANOMATERIALS 2022; 12:nano12101782. [PMID: 35631004 PMCID: PMC9146788 DOI: 10.3390/nano12101782] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 05/13/2022] [Accepted: 05/21/2022] [Indexed: 12/10/2022]
Abstract
The magnetic properties of nanocrystalline MxFe3-xO4 ferrites with M=Fe, Co, and Zn were investigated. The data support a core-shell model, where the core is ferrimagnetically ordered, and the shell shows a spin glass type behavior. The reduced magnetizations of spin glass components follow an mg = (1 - b/H-1/2) field dependence. The b values are strongly correlated with the intensities of exchange interactions. The field dependences of the magnetoresistances of Fe3O4 and ZnxFe3-xO4 nanoparticles pellets, experimentally determined, are well described if instead of the core reduced magnetization, commonly used, that of the shell is taken into account. For similar compositions of the nanoparticles, identical b values are obtained both from magnetization isotherms and magnetoresistances studies. The half-metallic behavior of spinel Fe3O4 based nanoparticles is discussed comparatively with those of double perovskites.
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Affiliation(s)
- Emil Burzo
- Correspondence: (E.B.); (R.T.); Tel.: +40-624405300 (ext. 5164) (R.T.)
| | - Romulus Tetean
- Correspondence: (E.B.); (R.T.); Tel.: +40-624405300 (ext. 5164) (R.T.)
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4
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Dardzinski D, Yu M, Moayedpour S, Marom N. Best practices for first-principles simulations of epitaxial inorganic interfaces. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:233002. [PMID: 35193122 DOI: 10.1088/1361-648x/ac577b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 02/22/2022] [Indexed: 06/14/2023]
Abstract
At an interface between two materials physical properties and functionalities may be achieved, which would not exist in either material alone. Epitaxial inorganic interfaces are at the heart of semiconductor, spintronic, and quantum devices. First principles simulations based on density functional theory (DFT) can help elucidate the electronic and magnetic properties of interfaces and relate them to the structure and composition at the atomistic scale. Furthermore, DFT simulations can predict the structure and properties of candidate interfaces and guide experimental efforts in promising directions. However, DFT simulations of interfaces can be technically elaborate and computationally expensive. To help researchers embarking on such simulations, this review covers best practices for first principles simulations of epitaxial inorganic interfaces, including DFT methods, interface model construction, interface structure prediction, and analysis and visualization tools.
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Affiliation(s)
- Derek Dardzinski
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United States of America
| | - Maituo Yu
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United States of America
| | - Saeed Moayedpour
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, United States of America
| | - Noa Marom
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United States of America
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, United States of America
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, United States of America
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5
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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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6
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Sønsteby HH, Skaar E, Fjellvåg ØS, Bratvold JE, Fjellvåg H, Nilsen O. A foundation for complex oxide electronics -low temperature perovskite epitaxy. Nat Commun 2020; 11:2872. [PMID: 32513928 PMCID: PMC7280286 DOI: 10.1038/s41467-020-16654-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 05/12/2020] [Indexed: 11/24/2022] Open
Abstract
As traditional silicon technology is moving fast towards its fundamental limits, all-oxide electronics is emerging as a challenger offering principally different electronic behavior and switching mechanisms. This technology can be utilized to fabricate devices with enhanced and exotic functionality. One of the challenges for integration of complex oxides in electronics is the availability of appreciable low-temperature synthesis routes. Herein we provide a fundamental extension of the materials toolbox for oxide electronics by reporting a facile route for deposition of highly electrically conductive thin films of LaNiO3 by atomic layer deposition at low temperatures. The films grow epitaxial on SrTiO3 and LaAlO3 as deposited at 225 °C, with no annealing required to obtain the attractive electronic properties. The films exhibit resistivity below 100 µΩ cm with carrier densities as high as 3.6 · 1022 cm−3. This marks an important step in the realization of all-oxide electronics for emerging technological devices. Designing complex oxides with appreciable low-temperature synthesis remains a challenge. Here, the authors demonstrate an atomic layer deposition process for LaNiO3 to enable epitaxial thin films on LaAlO3 and SrTiO3 substrates deposited at 225 °C, with no annealing required to achieve good electronic properties.
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Affiliation(s)
- Henrik H Sønsteby
- Department of Chemistry, Center for Materials Science and Nanotechnology, University of Oslo, Blindern, 0315, Oslo, Norway.
| | - Erik Skaar
- Department of Chemistry, Center for Materials Science and Nanotechnology, University of Oslo, Blindern, 0315, Oslo, Norway
| | - Øystein S Fjellvåg
- Department for Neutron Materials Characterization, Institute for Energy Technology, 2007, Kjeller, Norway
| | - Jon E Bratvold
- Department of Chemistry, Center for Materials Science and Nanotechnology, University of Oslo, Blindern, 0315, Oslo, Norway
| | - Helmer Fjellvåg
- Department of Chemistry, Center for Materials Science and Nanotechnology, University of Oslo, Blindern, 0315, Oslo, Norway
| | - Ola Nilsen
- Department of Chemistry, Center for Materials Science and Nanotechnology, University of Oslo, Blindern, 0315, Oslo, Norway
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7
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Li D, Lemal S, Gariglio S, Wu Z, Fête A, Boselli M, Ghosez P, Triscone J. Probing Quantum Confinement and Electronic Structure at Polar Oxide Interfaces. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2018; 5:1800242. [PMID: 30128239 PMCID: PMC6097152 DOI: 10.1002/advs.201800242] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 04/28/2018] [Indexed: 06/08/2023]
Abstract
Polar discontinuities occurring at interfaces between two materials constitute both a challenge and an opportunity in the study and application of a variety of devices. In order to cure the large electric field occurring in such structures, a reconfiguration of the charge landscape sets in at the interface via chemical modifications, adsorbates, or charge transfer. In the latter case, one may expect a local electronic doping of one material: one example is the two-dimensional electron liquid (2DEL) appearing in SrTiO3 once covered by a polar LaAlO3 layer. Here, it is shown that tuning the formal polarization of a (La,Al)1-x (Sr,Ti) x O3 (LASTO:x) overlayer modifies the quantum confinement of the 2DEL in SrTiO3 and its electronic band structure. The analysis of the behavior in magnetic field of superconducting field-effect devices reveals, in agreement with ab initio calculations and self-consistent Poisson-Schrödinger modeling, that quantum confinement and energy splitting between electronic bands of different symmetries strongly depend on the interface total charge densities. These results strongly support the polar discontinuity mechanisms with a full charge transfer to explain the origin of the 2DEL at the celebrated LaAlO3/SrTiO3 interface and demonstrate an effective tool for tailoring the electronic structure at oxide interfaces.
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Affiliation(s)
- Danfeng Li
- Department of Quantum Matter PhysicsUniversity of Geneva24 quai Ernest‐AnsermetCH‐1211Geneva 4Switzerland
| | - Sébastien Lemal
- Theoretical Materials PhysicsQ‐MATCESAMUniversité de LiègeB‐4000LiègeBelgium
| | - Stefano Gariglio
- Department of Quantum Matter PhysicsUniversity of Geneva24 quai Ernest‐AnsermetCH‐1211Geneva 4Switzerland
| | - Zhenping Wu
- Department of Quantum Matter PhysicsUniversity of Geneva24 quai Ernest‐AnsermetCH‐1211Geneva 4Switzerland
- State Key Laboratory of Information Photonics and Optical Communications and School of ScienceBeijing University of Posts and TelecommunicationsBeijing100876China
| | - Alexandre Fête
- Department of Quantum Matter PhysicsUniversity of Geneva24 quai Ernest‐AnsermetCH‐1211Geneva 4Switzerland
| | - Margherita Boselli
- Department of Quantum Matter PhysicsUniversity of Geneva24 quai Ernest‐AnsermetCH‐1211Geneva 4Switzerland
| | - Philippe Ghosez
- Theoretical Materials PhysicsQ‐MATCESAMUniversité de LiègeB‐4000LiègeBelgium
| | - Jean‐Marc Triscone
- Department of Quantum Matter PhysicsUniversity of Geneva24 quai Ernest‐AnsermetCH‐1211Geneva 4Switzerland
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8
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Pai YY, Tylan-Tyler A, Irvin P, Levy J. Physics of SrTiO 3-based heterostructures and nanostructures: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2018; 81:036503. [PMID: 29424362 DOI: 10.1088/1361-6633/aa892d] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
This review provides a summary of the rich physics expressed within SrTiO3-based heterostructures and nanostructures. The intended audience is researchers who are working in the field of oxides, but also those with different backgrounds (e.g., semiconductor nanostructures). After reviewing the relevant properties of SrTiO3 itself, we will then discuss the basics of SrTiO3-based heterostructures, how they can be grown, and how devices are typically fabricated. Next, we will cover the physics of these heterostructures, including their phase diagram and coupling between the various degrees of freedom. Finally, we will review the rich landscape of quantum transport phenomena, as well as the devices that elicit them.
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Affiliation(s)
- Yun-Yi Pai
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, United States of America. Pittsburgh Quantum Institute, Pittsburgh, PA 15260, United States of America
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9
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Chen H, Millis A. Charge transfer driven emergent phenomena in oxide heterostructures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:243001. [PMID: 28437253 DOI: 10.1088/1361-648x/aa6efe] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Complex oxides exhibit many intriguing phenomena, including metal-insulator transition, ferroelectricity/multiferroicity, colossal magnetoresistance and high transition temperature superconductivity. Advances in epitaxial thin film growth techniques enable us to combine different complex oxides with atomic precision and form an oxide heterostructure. Recent theoretical and experimental work has shown that charge transfer across oxide interfaces generally occurs and leads to a great diversity of emergent interfacial properties which are not exhibited by bulk constituents. In this report, we review mechanisms and physical consequence of charge transfer across interfaces in oxide heterostructures. Both theoretical proposals and experimental measurements of various oxide heterostructures are discussed and compared. We also review the theoretical methods that are used to calculate charge transfer across oxide interfaces and discuss the success and challenges in theory. Finally, we present a summary and perspectives for future research.
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Affiliation(s)
- Hanghui Chen
- NYU-ECNU Institute of Physics, New York University Shanghai, 200062, People's Republic of China. Department of Physics, New York University, New York, NY 10002, United States of America
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10
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Iida K, Nobusada K. Atomically modified thin interface in metal-dielectric hetero-integrated systems: control of electronic properties. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:145503. [PMID: 28248650 DOI: 10.1088/1361-648x/aa5e81] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We have performed first-principles studies of the electronic properties of Cu-diamond hetero-integrated systems, particularly placing emphasis on elucidating the effects of surface modification of diamond with H or O. It is found that the electronic properties crucially depend on the chemical compositions of the modified atomically thin interface region. The local density of states (LDOS) of the H-terminated diamond moiety near the Cu surface exhibits a clearly different distribution from that near the vacuum region, whereas the LDOS of the O-terminated diamond is almost independent of the Cu deposition. In other words, the effects of the electronic interactions between Cu and diamond on the electronic properties in the interface region are readily controlled by surface modification with only one atomic (i.e. H or O) layer. Electric field (EF) effects on the Cu-diamond systems also strongly depend on the electronic details, i.e. atomistic modification in the interface regions. In particular, at the interface between the H-terminated diamond moiety and the vacuum region, its conduction band energy is strongly affected by an applied EF much more than the valence band energy; that is, the band gap can be varied with an applied EF. The band gap variation is found to be attributed to an atomistic level difference in the spatial extension of the valence and conduction bands and thus is not explained with a macroscopic band diagram model. It has been demonstrated that the electronic properties of hetero-integrated systems are described and controlled well by carefully designing atomically thin interface regions.
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Affiliation(s)
- Kenji Iida
- Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Myodaiji, Okazaki, 444-8585, Japan
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11
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Nakamura M, Kagawa F, Tanigaki T, Park HS, Matsuda T, Shindo D, Tokura Y, Kawasaki M. Spontaneous Polarization and Bulk Photovoltaic Effect Driven by Polar Discontinuity in LaFeO_{3}/SrTiO_{3} Heterojunctions. PHYSICAL REVIEW LETTERS 2016; 116:156801. [PMID: 27127978 DOI: 10.1103/physrevlett.116.156801] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Indexed: 06/05/2023]
Abstract
Structurally coherent and chemically abrupt interfaces formed between polar and nonpolar perovskite oxides provide an ideal platform for examining the purely electronic reconstruction known as the polar catastrophe and the emergence of mobile or bound charges at the interface. The appearance of mobile charges induced by the polar catastrophe is already established in the LaAlO_{3}/SrTiO_{3} heterojunctions. Although not experimentally verified, the polar catastrophe can also lead to the emergence of spontaneous polarization. We report that thin films of originally nonpolar LaFeO_{3} grown on SrTiO_{3} are converted to polar as a consequence of the polar catastrophe. The induced spontaneous polarization evokes photovoltaic properties distinct from conventional p-n junctions, such as a switching of the photocurrent direction by changing the interfacial atomic sequence. The control of the bulk polarization by engineering the interface demonstrated here will expand the possibilities for designing and realizing new polar materials with photovoltaic functions.
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Affiliation(s)
- M Nakamura
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - F Kagawa
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - T Tanigaki
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - H S Park
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - T Matsuda
- Japan Science and Technology Agency (JST), Kawaguchi 332-0012, Japan
| | - D Shindo
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Y Tokura
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Department of Applied Physics and Quantum Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan
| | - M Kawasaki
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Department of Applied Physics and Quantum Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan
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12
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Strelcov E, Belianinov A, Hsieh YH, Chu YH, Kalinin SV. Constraining Data Mining with Physical Models: Voltage- and Oxygen Pressure-Dependent Transport in Multiferroic Nanostructures. NANO LETTERS 2015; 15:6650-6657. [PMID: 26312554 DOI: 10.1021/acs.nanolett.5b02472] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Development of new generation electronic devices necessitates understanding and controlling the electronic transport in ferroic, magnetic, and optical materials, which is hampered by two factors. First, the complications of working at the nanoscale, where interfaces, grain boundaries, defects, and so forth, dictate the macroscopic characteristics. Second, the convolution of the response signals stemming from the fact that several physical processes may be activated simultaneously. Here, we present a method of solving these challenges via a combination of atomic force microscopy and data mining analysis techniques. Rational selection of the latter allows application of physical constraints and enables direct interpretation of the statistically significant behaviors in the framework of the chosen physical model, thus distilling physical meaning out of raw data. We demonstrate our approach with an example of deconvolution of complex transport behavior in a bismuth ferrite-cobalt ferrite nanocomposite in ambient and ultrahigh vacuum environments. Measured signal is apportioned into four electronic transport patterns, showing different dependence on partial oxygen and water vapor pressure. These patterns are described in terms of Ohmic conductance and Schottky emission models in the light of surface electrochemistry. Furthermore, deep data analysis allows extraction of local dopant concentrations and barrier heights empowering our understanding of the underlying dynamic mechanisms of resistive switching.
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Affiliation(s)
- Evgheni Strelcov
- Institute for Functional Imaging of Materials and Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Alexei Belianinov
- Institute for Functional Imaging of Materials and Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Ying-Hui Hsieh
- Department of Materials Science and Engineering, National Chiao Tung University , Hsinchu 30010, Taiwan
| | - Ying-Hao Chu
- Department of Materials Science and Engineering, National Chiao Tung University , Hsinchu 30010, Taiwan
- Institute of Physics, Academia Sinica , Taipei 105, Taiwan
| | - Sergei V Kalinin
- Institute for Functional Imaging of Materials and Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
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13
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Gibertini M, Marzari N. Emergence of One-Dimensional Wires of Free Carriers in Transition-Metal-Dichalcogenide Nanostructures. NANO LETTERS 2015; 15:6229-38. [PMID: 26291826 DOI: 10.1021/acs.nanolett.5b02834] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
We highlight the emergence of metallic states in two-dimensional transition-metal-dichalcogenide nanostructures-nanoribbons, islands, and inversion domain boundaries-as a widespread and universal phenomenon driven by the polar discontinuities occurring at their edges or boundaries. We show that such metallic states form one-dimensional wires of electrons or holes, with a free charge density that increases with the system size, up to complete screening of the polarization charge, and can also be controlled by the specific edge or boundary configurations, e.g., through chemisorption of hydrogen or sulfur atoms at the edges. For triangular islands, local polar discontinuities occur even in the absence of a total dipole moment for the island and lead to an accumulation of free carriers close to the edges, providing a consistent explanation of previous experimental observations. To further stress the universal character of these mechanisms, we show that polar discontinuities give rise to metallic states also at inversion domain boundaries. These findings underscore the potential of engineering transition-metal-dichalcogenide nanostructures for manifold applications in nano- and optoelectronics, spintronics, catalysis, and solar-energy harvesting.
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Affiliation(s)
- Marco Gibertini
- Theory and Simulation of Materials (THEOS) and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), École Polytechnique Fédérale de Lausanne , CH-1015 Lausanne, Switzerland
| | - Nicola Marzari
- Theory and Simulation of Materials (THEOS) and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), École Polytechnique Fédérale de Lausanne , CH-1015 Lausanne, Switzerland
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14
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Bristowe NC, Ghosez P, Littlewood PB, Artacho E. The origin of two-dimensional electron gases at oxide interfaces: insights from theory. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:143201. [PMID: 24637267 DOI: 10.1088/0953-8984/26/14/143201] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The response of oxide thin films to polar discontinuities at interfaces and surfaces has generated enormous activity due to the variety of interesting effects that it gives rise to. A case in point is the discovery of the electron gas at the interface between LaAlO3 and SrTiO3, which has since been shown to be quasi-two-dimensional, switchable, magnetic and/or superconducting. Despite these findings, the origin of the two-dimensional electron gas is highly debated and several possible mechanisms remain. Here we review the main proposed mechanisms and attempt to model expected effects in a quantitative way with the ambition of better constraining what effects can/cannot explain the observed phenomenology. We do it in the framework of a phenomenological model constructed to provide an understanding of the electronic and/or redox screening of the chemical charge in oxide heterostructures. We also discuss the effect of intermixing, both conserving and not conserving the total stoichiometry.
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Affiliation(s)
- N C Bristowe
- Theoretical Materials Physics, University of Liège, B-4000 Sart-Tilman, Belgium. Theory of Condensed Matter, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, UK
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Suppression of the two-dimensional electron gas in LaGaO3/SrTiO3 by cation intermixing. Sci Rep 2013; 3:3409. [PMID: 24296477 PMCID: PMC3847700 DOI: 10.1038/srep03409] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 11/18/2013] [Indexed: 11/09/2022] Open
Abstract
Cation intermixing at the n-type polar LaGaO3/SrTiO3 (001) interface is investigated by first principles calculations. Ti⇔Ga, Sr⇔La, and SrTi⇔LaGa intermixing are studied in comparison to each other, with a focus on the interface stability. We demonstrate in which cases intermixing is energetically favorable as compared to a clean interface. A depopulation of the Ti 3dxy orbitals under cation intermixing is found, reflecting a complete suppression of the two-dimensional electron gas present at the clean interface.
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16
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Doennig D, Pickett WE, Pentcheva R. Massive symmetry breaking in LaAlO3/SrTiO3(111) quantum wells: a three-orbital strongly correlated generalization of graphene. PHYSICAL REVIEW LETTERS 2013; 111:126804. [PMID: 24093290 DOI: 10.1103/physrevlett.111.126804] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Indexed: 06/02/2023]
Abstract
Density functional theory calculations with an on-site Coulomb repulsion term reveal competing ground states in (111)-oriented (LaAlO(3))(M)/(SrTiO(3))(N) superlattices with n-type interfaces, ranging from spin, orbitally polarized (with selective e(g)('), a(1g), or d(xy) occupation), Dirac point Fermi surface, to charge-ordered flat band phases. These phases are steered by the interplay of (i) Hubbard U, (ii) SrTiO(3) quantum well thickness, and (iii) crystal field splitting tied to in-plane strain. In the honeycomb lattice bilayer N = 2 under tensile strain, inversion symmetry breaking drives the system from a ferromagnetic Dirac point (massless Weyl semimetal) to a charge-ordered multiferroic (ferromagnetic and ferroelectric) flat band massive (insulating) phase. With increasing SrTiO(3) quantum well thickness an insulator-to-metal transition occurs.
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Affiliation(s)
- David Doennig
- Department of Earth and Environmental Sciences, Section Crystallography and Center of Nanoscience, University of Munich, Theresienstrasse 41, 80333 Munich, Germany
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Salluzzo M, Gariglio S, Torrelles X, Ristic Z, Di Capua R, Drnec J, Sala MM, Ghiringhelli G, Felici R, Brookes NB. Structural and electronic reconstructions at the LaAlO₃/SrTiO₃ interface. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2013; 25:2333-2332. [PMID: 23382034 DOI: 10.1002/adma.201204555] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Revised: 12/17/2012] [Indexed: 06/01/2023]
Affiliation(s)
- M Salluzzo
- CNR-SPIN and Department of Physics, Complesso MonteSantangelo via Cinthia, I-80126 Napoli, Italy.
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18
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Nazir S, Schwingenschlögl U. Virtual half-metallicity at the CoS2/FeS2 interface induced by strain. RSC Adv 2013. [DOI: 10.1039/c3ra22184a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Huang BC, Chiu YP, Huang PC, Wang WC, Tra VT, Yang JC, He Q, Lin JY, Chang CS, Chu YH. Mapping band alignment across complex oxide heterointerfaces. PHYSICAL REVIEW LETTERS 2012; 109:246807. [PMID: 23368366 DOI: 10.1103/physrevlett.109.246807] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Indexed: 06/01/2023]
Abstract
In this study, direct observation of the evolution of electronic structures across complex oxide interfaces has been revealed in the LaAlO(3)/SrTiO(3) model system using cross-sectional scanning tunneling microscopy and spectroscopy. The conduction and valence band structures across the LaAlO(3)/SrTiO(3) interface are spatially resolved at the atomic level by measuring the local density of states. This study directly maps out the electronic reconstructions and a built-in electric field in the polar LaAlO(3) layer. Results also clearly reveal the band bending and the notched band structure in the SrTiO(3) adjacent to the interface.
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Affiliation(s)
- Bo-Chao Huang
- Department of Physics, National Sun Yat-sen University, Kaohsiung 804, Taiwan
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20
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Pentcheva R, Arras R, Otte K, Ruiz VG, Pickett WE. Termination control of electronic phases in oxide thin films and interfaces: LaAlO3/SrTiO3(001). PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2012; 370:4904-4926. [PMID: 22987035 DOI: 10.1098/rsta.2012.0202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A wealth of intriguing properties emerge in the seemingly simple system composed of the band insulators LaAlO(3) and SrTiO(3) such as a two-dimensional electron gas, superconductivity and magnetism. In this paper, we review the current insight obtained from first principles calculations on the mechanisms governing the behaviour of thin LaAlO(3) films on SrTiO(3)(001). In particular, we explore the strong dependence of the electronic properties on the surface and interface termination, the finite film thickness, lattice polarization and defects. A further aspect that is addressed is how the electronic behaviour and functionality can be tuned by an SrTiO(3) capping layer, adsorbates and metallic contacts. Lastly, we discuss recent reports on the coexistence of magnetism and superconductivity in this system for what they might imply about the electronic structure of this system.
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Affiliation(s)
- R Pentcheva
- Department of Earth and Environmental Sciences, Section Crystallography and Center of Nanoscience, University of Munich, Germany.
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21
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Rondinelli JM, Spaldin NA. Structure and properties of functional oxide thin films: insights from electronic-structure calculations. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2011; 23:3363-3381. [PMID: 21748811 DOI: 10.1002/adma.201101152] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Indexed: 05/27/2023]
Abstract
The confluence of state-of-the-art electronic-structure computations and modern synthetic materials growth techniques is proving indispensable in the search for and discovery of new functionalities in oxide thin films and heterostructures. Here, we review the recent contributions of electronic-structure calculations to predicting, understanding, and discovering new materials physics in thin-film perovskite oxides. We show that such calculations can accurately predict both structure and properties in advance of film synthesis, thereby guiding the search for materials combinations with specific targeted functionalities. In addition, because they can isolate and decouple the effects of various parameters which unavoidably occur simultaneously in an experiment-such as epitaxial strain, interfacial chemistry and defect profiles-they are able to provide new fundamental knowledge about the underlying physics. We conclude by outlining the limitations of current computational techniques, as well as some important open questions that we hope will motivate further methodological developments in the field.
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Affiliation(s)
- James M Rondinelli
- X-Ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
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22
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Stengel M. First-principles modeling of electrostatically doped perovskite systems. PHYSICAL REVIEW LETTERS 2011; 106:136803. [PMID: 21517406 DOI: 10.1103/physrevlett.106.136803] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2010] [Indexed: 05/30/2023]
Abstract
Macroscopically, confined electron gases at polar oxide interfaces are rationalized within the simple "polar catastrophe" model. At the microscopic level, however, many other effects such as electric fields, structural distortions and quantum-mechanical interactions enter into play. Here, we show how to bridge the gap between these two length scales, by combining the accuracy of first-principles methods with the conceptual simplicity of model Hamiltonian approaches. To demonstrate our strategy, we address the equilibrium distribution of the compensating free carriers at polar LaAlO(3)/SrTiO(3) interfaces. Remarkably, a model including only calculated bulk properties of SrTiO(3) and no adjustable parameters accurately reproduces our full first-principles results. Our strategy provides a unified description of charge compensation mechanisms in SrTiO(3)-based systems.
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Affiliation(s)
- Massimiliano Stengel
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra, Spain.
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