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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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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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3
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Brown JJ, Page AJ. Reaction pathways in the solid state and the Hubbard U correction. J Chem Phys 2021; 154:124121. [PMID: 33810657 DOI: 10.1063/5.0045526] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
We investigate how the Hubbard U correction influences vacancy defect migration barriers in transition metal oxide semiconductors. We show that, depending on the occupation of the transition metal d orbitals, the Hubbard U correction can cause severe instabilities in the migration barrier energies predicted using generalized gradient approximation density functional theory (GGA DFT). For the d0 oxide SrTiO3, applying a Hubbard correction to the Ti4+ 3d orbitals below 4-5 eV yields a migration barrier of ∼0.4 eV. However, above this threshold, the barrier increases suddenly to ∼2 eV. This sudden increase in the transition state barrier arises from the Hubbard U correction changing the Ti4+ t2g/eg orbital occupation, and hence electron density localization, along the migration pathway. Similar results are observed in the d10 oxide ZnO; however, significantly larger Hubbard U corrections must be applied to the Zn2+ 3d orbitals for the same instability to be observed. These results highlight important limitations to the application of the Hubbard U correction when modeling reactive pathways in solid state materials using GGA DFT.
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Affiliation(s)
- Joshua J Brown
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW 2308, Australia
| | - Alister J Page
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW 2308, Australia
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Meyers D, Cao Y, Fabbris G, Robinson NJ, Hao L, Frederick C, Traynor N, Yang J, Lin J, Upton MH, Casa D, Kim JW, Gog T, Karapetrova E, Choi Y, Haskel D, Ryan PJ, Horak L, Liu X, Liu J, Dean MPM. Magnetism in iridate heterostructures leveraged by structural distortions. Sci Rep 2019; 9:4263. [PMID: 30862782 PMCID: PMC6414659 DOI: 10.1038/s41598-019-39422-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 01/18/2019] [Indexed: 11/09/2022] Open
Abstract
Fundamental control of magnetic coupling through heterostructure morphology is a prerequisite for rational engineering of magnetic ground states. We report the tuning of magnetic interactions in superlattices composed of single and bilayers of SrIrO3 inter-spaced with SrTiO3 in analogy to the Ruddlesden-Popper series iridates. Magnetic scattering shows predominately c-axis antiferromagnetic orientation of the magnetic moments for the bilayer, as in Sr3Ir2O7. However, the magnetic excitation gap, measured by resonant inelastic x-ray scattering, is quite different between the two structures, evidencing a significant change in the stability of the competing magnetic phases. In contrast, the single layer iridate hosts a more bulk-like gap. We find these changes are driven by bending of the c-axis Ir-O-Ir bond, which is much weaker in the single layer, and subsequent local environment changes, evidenced through x-ray diffraction and magnetic excitation modeling. Our findings demonstrate how large changes in the magnetic interactions can be tailored and probed in spin-orbit coupled heterostructures by engineering subtle structural modulations.
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Affiliation(s)
- D Meyers
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York, 11973, USA.
| | - Yue Cao
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York, 11973, USA
| | - G Fabbris
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York, 11973, USA
| | - Neil J Robinson
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York, 11973, USA
| | - Lin Hao
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee, 37996, USA
| | - C Frederick
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee, 37996, USA
| | - N Traynor
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee, 37996, USA
| | - J Yang
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee, 37996, USA
| | - Jiaqi Lin
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.,School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - M H Upton
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, 60439, USA
| | - D Casa
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, 60439, USA
| | - Jong-Woo Kim
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, 60439, USA
| | - T Gog
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, 60439, USA
| | - E Karapetrova
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, 60439, USA
| | - Yongseong Choi
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, 60439, USA
| | - D Haskel
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, 60439, USA
| | - P J Ryan
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, 60439, USA.,School of Physical Sciences, Dublin City University, Dublin 9, Ireland
| | - Lukas Horak
- Department of Condensed Matter Physics, Charles University, Ke Karlovu 3, Prague, 12116, Czech Republic
| | - X Liu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.,Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Jian Liu
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee, 37996, USA.
| | - M P M Dean
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York, 11973, USA.
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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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Facing the phase problem in Coherent Diffractive Imaging via Memetic Algorithms. Sci Rep 2017; 7:42236. [PMID: 28181592 PMCID: PMC5299835 DOI: 10.1038/srep42236] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 01/06/2017] [Indexed: 11/20/2022] Open
Abstract
Coherent Diffractive Imaging is a lensless technique that allows imaging of matter at a spatial resolution not limited by lens aberrations. This technique exploits the measured diffraction pattern of a coherent beam scattered by periodic and non–periodic objects to retrieve spatial information. The diffracted intensity, for weak–scattering objects, is proportional to the modulus of the Fourier Transform of the object scattering function. Any phase information, needed to retrieve its scattering function, has to be retrieved by means of suitable algorithms. Here we present a new approach, based on a memetic algorithm, i.e. a hybrid genetic algorithm, to face the phase problem, which exploits the synergy of deterministic and stochastic optimization methods. The new approach has been tested on simulated data and applied to the phasing of transmission electron microscopy coherent electron diffraction data of a SrTiO3 sample. We have been able to quantitatively retrieve the projected atomic potential, and also image the oxygen columns, which are not directly visible in the relevant high-resolution transmission electron microscopy images. Our approach proves to be a new powerful tool for the study of matter at atomic resolution and opens new perspectives in those applications in which effective phase retrieval is necessary.
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