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Title: Epitaxial thin films of pyrochlore iridate Bi 2+xIr 2-yO 7-δ: structure, defects and transport properties

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. We report on the pulsed laser deposition and characterization of thin films of a representative pyrochlore compound Bi 2Ir 2O 7. Moreover, 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.
Authors:
 [1] ;  [2] ;  [1] ;  [2] ; ORCiD logo [3] ;  [4] ;  [5] ;  [1] ;  [1] ;  [1] ;  [2] ;  [3] ; ORCiD logo [6] ;  [2] ;  [1]
  1. Indiana Univ., Bloomington, IN (United States). Dept. of Physics
  2. Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States). Dept. of Physics
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Center for Integrated Nanotechnologies
  4. Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry
  5. Indiana Univ., Bloomington, IN (United States). Dept. of Physics; Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Center for Integrated Nanotechnologies
  6. Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Center for Integrated Nanotechnologies; State Univ. of New York (SUNY), Buffalo, NY (United States). Dept. of Materials Design and Innovation
Publication Date:
Report Number(s):
LA-UR-17-24496
Journal ID: ISSN 2045-2322
Grant/Contract Number:
AC52-06NA2539
Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 7; Journal Issue: 1; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; electronic properties and materials; surfaces, interfaces and thin films
OSTI Identifier:
1396132

Yang, W. C., Xie, Y. T., Zhu, W. K., Park, K., Chen, A. P., Losovyj, Y., Li, Z., Liu, H. M., Starr, M., Acosta, J. A., Tao, C. G., Li, N., Jia, Q. X., Heremans, J. J., and Zhang, S. X.. Epitaxial thin films of pyrochlore iridate Bi2+xIr2-yO7-δ: structure, defects and transport properties. United States: N. p., Web. doi:10.1038/s41598-017-06785-w.
Yang, W. C., Xie, Y. T., Zhu, W. K., Park, K., Chen, A. P., Losovyj, Y., Li, Z., Liu, H. M., Starr, M., Acosta, J. A., Tao, C. G., Li, N., Jia, Q. X., Heremans, J. J., & Zhang, S. X.. Epitaxial thin films of pyrochlore iridate Bi2+xIr2-yO7-δ: structure, defects and transport properties. United States. doi:10.1038/s41598-017-06785-w.
Yang, W. C., Xie, Y. T., Zhu, W. K., Park, K., Chen, A. P., Losovyj, Y., Li, Z., Liu, H. M., Starr, M., Acosta, J. A., Tao, C. G., Li, N., Jia, Q. X., Heremans, J. J., and Zhang, S. X.. 2017. "Epitaxial thin films of pyrochlore iridate Bi2+xIr2-yO7-δ: structure, defects and transport properties". United States. doi:10.1038/s41598-017-06785-w. https://www.osti.gov/servlets/purl/1396132.
@article{osti_1396132,
title = {Epitaxial thin films of pyrochlore iridate Bi2+xIr2-yO7-δ: structure, defects and transport properties},
author = {Yang, W. C. and Xie, Y. T. and Zhu, W. K. and Park, K. and Chen, A. P. and Losovyj, Y. and Li, Z. and Liu, H. M. and Starr, M. and Acosta, J. A. and Tao, C. G. and Li, N. and Jia, Q. X. and Heremans, J. J. and Zhang, S. X.},
abstractNote = {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. We report on the pulsed laser deposition and characterization of thin films of a representative pyrochlore compound Bi2Ir2O7. Moreover, 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.},
doi = {10.1038/s41598-017-06785-w},
journal = {Scientific Reports},
number = 1,
volume = 7,
place = {United States},
year = {2017},
month = {8}
}

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