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Ghosh M, Bhat SG, Pal A, Kumar PSA. Tuning the semimetallic charge transport in the Weyl semimetal candidate Eu 2Ir 2O 7(111) epitaxial thin film with an all-in-all-out spin structure. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:165701. [PMID: 35105826 DOI: 10.1088/1361-648x/ac50da] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 02/01/2022] [Indexed: 06/14/2023]
Abstract
We report the stoichiometric epitaxial growth of the Eu2Ir2O7(111) thin film on YSZ substrate by a two-step solid phase epitaxy (SPE) method. An optimized post-annealing environment of the SPE was superior over the conventional air annealing procedure to get rid of the typical impurity phase, Eu2O3. The thickness-dependent structural study on Eu2Ir2O7(111) thin films suggests a systematic control of Ir/Eu stoichiometry in our films, which is otherwise difficult to achieve. In addition, the low-temperature electrical resistivity studies strongly support the claim. The power-law dependence analysis of the resistivity data exhibits a power exponent of 0.52 in 50 nm sample suggesting possible disorder-driven semimetallic charge transport in the 3D Weyl semimetallic (WSM) candidate Eu2Ir2O7. In addition, the all-in-all-out/all-out-all-in antiferromagnetic domains of Ir4+sublattice is verified using the field cooled magnetoresistance measurements at 2 K. Hall resistivity analysis indicate semimetallic hole carrier type dominance near the Fermi level up to the measured temperature range of 2-120 K. Altogether, our study reveals the ground state of stoichiometric Eu2Ir2O7(111) thin film, with an indirect tuning of the off-stoichiometry using thickness of the samples, which is of interest in the search of the predicted 3D WSM phase.
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Affiliation(s)
- Mithun Ghosh
- Department of Physics, Indian Institute of Science, Bangalore 560012, Karnataka, India
| | - Shwetha G Bhat
- Department of Physics, Indian Institute of Science, Bangalore 560012, Karnataka, India
| | - Anand Pal
- Department of Physics, Indian Institute of Science, Bangalore 560012, Karnataka, India
- Department of Physics, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal-576104, Karnataka, India
| | - P S Anil Kumar
- Department of Physics, Indian Institute of Science, Bangalore 560012, Karnataka, India
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Wardini JL, Vahidi H, Guo H, Bowman WJ. Probing Multiscale Disorder in Pyrochlore and Related Complex Oxides in the Transmission Electron Microscope: A Review. Front Chem 2021; 9:743025. [PMID: 34917587 PMCID: PMC8668443 DOI: 10.3389/fchem.2021.743025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Accepted: 10/15/2021] [Indexed: 11/13/2022] Open
Abstract
Transmission electron microscopy (TEM), and its counterpart, scanning TEM (STEM), are powerful materials characterization tools capable of probing crystal structure, composition, charge distribution, electronic structure, and bonding down to the atomic scale. Recent (S)TEM instrumentation developments such as electron beam aberration-correction as well as faster and more efficient signal detection systems have given rise to new and more powerful experimental methods, some of which (e.g., 4D-STEM, spectrum-imaging, in situ/operando (S)TEM)) facilitate the capture of high-dimensional datasets that contain spatially-resolved structural, spectroscopic, time- and/or stimulus-dependent information across the sub-angstrom to several micrometer length scale. Thus, through the variety of analysis methods available in the modern (S)TEM and its continual development towards high-dimensional data capture, it is well-suited to the challenge of characterizing isometric mixed-metal oxides such as pyrochlores, fluorites, and other complex oxides that reside on a continuum of chemical and spatial ordering. In this review, we present a suite of imaging and diffraction (S)TEM techniques that are uniquely suited to probe the many types, length-scales, and degrees of disorder in complex oxides, with a focus on disorder common to pyrochlores, fluorites and the expansive library of intermediate structures they may adopt. The application of these techniques to various complex oxides will be reviewed to demonstrate their capabilities and limitations in resolving the continuum of structural and chemical ordering in these systems.
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Affiliation(s)
- Jenna L. Wardini
- Materials Science and Engineering, University of California, Irvine, Irvine, CA, United States
| | - Hasti Vahidi
- Materials Science and Engineering, University of California, Irvine, Irvine, CA, United States
| | - Huiming Guo
- Materials Science and Engineering, University of California, Irvine, Irvine, CA, United States
| | - William J. Bowman
- Materials Science and Engineering, University of California, Irvine, Irvine, CA, United States
- Irvine Materials Research Institute, Irvine, CA, United States
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3
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Kim WJ, Oh T, Song J, Ko EK, Li Y, Mun J, Kim B, Son J, Yang Z, Kohama Y, Kim M, Yang BJ, Noh TW. Strain engineering of the magnetic multipole moments and anomalous Hall effect in pyrochlore iridate thin films. SCIENCE ADVANCES 2020; 6:eabb1539. [PMID: 32832638 PMCID: PMC7439458 DOI: 10.1126/sciadv.abb1539] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 05/29/2020] [Indexed: 05/31/2023]
Abstract
The recent observation of the anomalous Hall effect (AHE) without notable magnetization in antiferromagnets has suggested that ferromagnetic ordering is not a necessary condition. Thus, recent theoretical studies have proposed that higher-rank magnetic multipoles formed by clusters of spins (cluster multipoles) can generate the AHE without magnetization. Despite such an intriguing proposal, controlling the unconventional AHE by inducing these cluster multipoles has not been investigated. Here, we demonstrate that strain can manipulate the hidden Berry curvature effect by inducing the higher-rank cluster multipoles in spin-orbit-coupled antiferromagnets. Observing the large AHE on fully strained antiferromagnetic Nd2Ir2O7 thin films, we prove that strain-induced cluster T 1-octupoles are the only source of observed AHE. Our results provide a previously unidentified pathway for generating the unconventional AHE via strain-induced magnetic structures and establish a platform for exploring undiscovered topological phenomena via strain in correlated materials.
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Affiliation(s)
- Woo Jin Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Taekoo Oh
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
- Center for Theoretical Physics (CTP), Seoul National University, Seoul 08826, Republic of Korea
| | - Jeongkeun Song
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Eun Kyo Ko
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Yangyang Li
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Junsik Mun
- Department of Materials Science and Engineering and Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
| | - Bongju Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Jaeseok Son
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Zhuo Yang
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Yoshimitsu Kohama
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Miyoung Kim
- Department of Materials Science and Engineering and Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
| | - Bohm-Jung Yang
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
- Center for Theoretical Physics (CTP), Seoul National University, Seoul 08826, Republic of Korea
| | - Tae Won Noh
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
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4
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Two-dimensional magnetic monopole gas in an oxide heterostructure. Nat Commun 2020; 11:1341. [PMID: 32165628 PMCID: PMC7067881 DOI: 10.1038/s41467-020-15213-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Accepted: 02/18/2020] [Indexed: 11/19/2022] Open
Abstract
Magnetic monopoles have been proposed as emergent quasiparticles in pyrochlore spin ice compounds. However, unlike semiconductors and two-dimensional electron gases where the charge degree of freedom can be actively controlled by chemical doping, interface modulation, and electrostatic gating, there is as of yet no analogue of these effects for emergent magnetic monopoles. To date, all experimental investigations have been limited to large ensembles comprised of equal numbers of monopoles and antimonopoles in bulk crystals. To address these issues, we propose the formation of a two-dimensional magnetic monopole gas (2DMG) with a net magnetic charge, confined at the interface between a spin ice and an isostructural antiferromagnetic pyrochlore iridate and whose monopole density can be controlled by an external field. Our proposal is based on Monte Carlo simulations of the thermodynamic and transport properties. This proposed 2DMG should enable experiments and devices which can be performed on magnetic monopoles, akin to two-dimensional electron gases in semiconductor heterostructures. Heterostructure interfaces have physical properties distinct from bulk materials, providing the basis for many electronic devices. Miao et al. propose a spin ice heterostructure that can host a two-dimensional gas of emergent magnetic monopoles with a net magnetic charge.
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Yang WC, Xie YT, Zhu WK, Park K, Chen AP, Losovyj Y, Li Z, Liu HM, Starr M, Acosta JA, Tao CG, Li N, Jia QX, Heremans JJ, Zhang SX. Epitaxial thin films of pyrochlore iridate Bi 2+xIr 2-yO 7-δ: structure, defects and transport properties. Sci Rep 2017; 7:7740. [PMID: 28798487 PMCID: PMC5552750 DOI: 10.1038/s41598-017-06785-w] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 05/15/2017] [Indexed: 11/09/2022] Open
Abstract
While pyrochlore iridate thin films are theoretically predicted to possess a variety of emergent topological properties, experimental verification of these predictions can be obstructed by the challenge in thin film growth. Here we report on the pulsed laser deposition and characterization of thin films of a representative pyrochlore compound Bi2Ir2O7. The films were epitaxially grown on yttria-stabilized zirconia substrates and have lattice constants that are a few percent larger than that of the bulk single crystals. The film composition shows a strong dependence on the oxygen partial pressure. Density-functional-theory calculations indicate the existence of BiIr antisite defects, qualitatively consistent with the high Bi: Ir ratio found in the films. Both Ir and Bi have oxidation states that are lower than their nominal values, suggesting the existence of oxygen deficiency. The iridate thin films show a variety of intriguing transport characteristics, including multiple charge carriers, logarithmic dependence of resistance on temperature, antilocalization corrections to conductance due to spin-orbit interactions, and linear positive magnetoresistance.
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Affiliation(s)
- W C Yang
- Department of Physics, Indiana University, Bloomington, Indiana, 47405, USA
| | - Y T Xie
- Department of Physics, Virginia Tech, Blacksburg, Virginia, 24061, USA
| | - W K Zhu
- Department of Physics, Indiana University, Bloomington, Indiana, 47405, USA
| | - K Park
- Department of Physics, Virginia Tech, Blacksburg, Virginia, 24061, USA
| | - A P Chen
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, 87545, USA
| | - Y Losovyj
- Department of Chemistry, Indiana University, Bloomington, Indiana, 47405, USA
| | - Z Li
- Department of Physics, Indiana University, Bloomington, Indiana, 47405, USA.,Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, 87545, USA
| | - H M Liu
- Department of Physics, Indiana University, Bloomington, Indiana, 47405, USA
| | - M Starr
- Department of Physics, Indiana University, Bloomington, Indiana, 47405, USA
| | - J A Acosta
- Department of Physics, Indiana University, Bloomington, Indiana, 47405, USA
| | - C G Tao
- Department of Physics, Virginia Tech, Blacksburg, Virginia, 24061, USA
| | - N Li
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, 87545, USA
| | - Q X Jia
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, 87545, USA.,Department of Materials Design and Innovation, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA
| | - J J Heremans
- Department of Physics, Virginia Tech, Blacksburg, Virginia, 24061, USA
| | - S X Zhang
- Department of Physics, Indiana University, Bloomington, Indiana, 47405, USA.
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