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Title: Electronic and structural response to pressure in the hyperkagome-lattice Na 3 Ir 3 O 8

Here, the hyper-kagome lattice iridate Na 3Ir 3O 8, closely related to spin liquid candidate Na 4Ir 3O 8, is unusual in that spin-orbit interactions acting on the 1/3-filled J eff = 1/2 state lead to a semimetallic ground state, in contrast to the conventional insulating Mott state stabilized by S-O interactions in the 1/2-filled J eff = 1/2 state of other iridates including Na 4Ir 3O 8. We have studied the evolution of crystal structure, electronic structure, and transport in Na 3Ir 3O 8 under high pressure using x-ray diffraction, x-ray absorption near edge structure, and electrical resistance measurements in a diamond anvil cell. The study was augmented by the use of ab initio calculations, which provided insight into pressure-induced changes in crystal and electronic structure. We found that Na 3Ir 3O 8 transforms from a semimetal to an insulator under pressure, with an estimated energy gap that increases to about 130 meV at P similar to 9 GPa. At approximately 10 GPa, a cubic-to-monoclinic structural transition takes place between two insulating phases. This structural transition features a sizable volume collapse and a high-pressure phase characterized by apparent dimerization of Ir-Ir distances, wide dispersion of Ir-O-Ir bond angles, andmore » an increase in the occupation of 5 d states. Although the energy gap is reduced in the high-pressure phase, insulating behavior remains to the highest pressures similar to 1 Mbar. The strongly pressure-dependent insulating gap shows a positive correlation with the expectation value of the angular part of the S-O interaction, < L • S >, which may indicate an active role of S-O interactions in stabilizing the insulating state that emerges in the compressed Na 3Ir 3O 8 structure.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [2] ;  [8] ;  [8] ;  [2] ;  [4] ;  [2]
  1. Center for High Pressure Science and Technology Advanced Research (HPSTAR), Beijing (China); Argonne National Lab. (ANL), Argonne, IL (United States); Chinese Academy of Sciences (CAS), Beijing (China)
  2. Argonne National Lab. (ANL), Argonne, IL (United States)
  3. Chinese Academy of Sciences (CAS), Beijing (China); Xi'an Modern Chemistry Research Institute, Xi'an (China)
  4. Binghamton Univ., State Univ. of New York, Binghamton, NY (United States)
  5. Center for High Pressure Science and Technology Advanced Research (HPSTAR), Beijing (China)
  6. Argonne National Lab. (ANL), Argonne, IL (United States); Northern Illinois Univ., DeKalb, IL (United States)
  7. Chinese Academy of Sciences (CAS), Beijing (China); Collaborative Innovation Center of Quantum Matter, Beijing (China)
  8. Center for High Pressure Science and Technology Advanced Research (HPSTAR), Beijing (China); Carnegie Inst. of Washington, Argonne, IL (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357; FG02-99ER45775; NA0001974
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 98; Journal Issue: 8; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1472084
Alternate Identifier(s):
OSTI ID: 1465243

Sun, F., Zheng, H., Liu, Y., Sandoval, E. D., Xu, C., Xu, J., Jin, C. Q., Sun, C. J., Yang, W. G., Mao, H. K., Mitchell, J. F., Kolmogorov, A. N., and Haskel, D.. Electronic and structural response to pressure in the hyperkagome-lattice Na3Ir3O8. United States: N. p., Web. doi:10.1103/PhysRevB.98.085131.
Sun, F., Zheng, H., Liu, Y., Sandoval, E. D., Xu, C., Xu, J., Jin, C. Q., Sun, C. J., Yang, W. G., Mao, H. K., Mitchell, J. F., Kolmogorov, A. N., & Haskel, D.. Electronic and structural response to pressure in the hyperkagome-lattice Na3Ir3O8. United States. doi:10.1103/PhysRevB.98.085131.
Sun, F., Zheng, H., Liu, Y., Sandoval, E. D., Xu, C., Xu, J., Jin, C. Q., Sun, C. J., Yang, W. G., Mao, H. K., Mitchell, J. F., Kolmogorov, A. N., and Haskel, D.. 2018. "Electronic and structural response to pressure in the hyperkagome-lattice Na3Ir3O8". United States. doi:10.1103/PhysRevB.98.085131.
@article{osti_1472084,
title = {Electronic and structural response to pressure in the hyperkagome-lattice Na3Ir3O8},
author = {Sun, F. and Zheng, H. and Liu, Y. and Sandoval, E. D. and Xu, C. and Xu, J. and Jin, C. Q. and Sun, C. J. and Yang, W. G. and Mao, H. K. and Mitchell, J. F. and Kolmogorov, A. N. and Haskel, D.},
abstractNote = {Here, the hyper-kagome lattice iridate Na3Ir3O8, closely related to spin liquid candidate Na4Ir3O8, is unusual in that spin-orbit interactions acting on the 1/3-filled Jeff = 1/2 state lead to a semimetallic ground state, in contrast to the conventional insulating Mott state stabilized by S-O interactions in the 1/2-filled Jeff = 1/2 state of other iridates including Na4Ir3O8. We have studied the evolution of crystal structure, electronic structure, and transport in Na3Ir3O8 under high pressure using x-ray diffraction, x-ray absorption near edge structure, and electrical resistance measurements in a diamond anvil cell. The study was augmented by the use of ab initio calculations, which provided insight into pressure-induced changes in crystal and electronic structure. We found that Na3Ir3O8 transforms from a semimetal to an insulator under pressure, with an estimated energy gap that increases to about 130 meV at P similar to 9 GPa. At approximately 10 GPa, a cubic-to-monoclinic structural transition takes place between two insulating phases. This structural transition features a sizable volume collapse and a high-pressure phase characterized by apparent dimerization of Ir-Ir distances, wide dispersion of Ir-O-Ir bond angles, and an increase in the occupation of 5d states. Although the energy gap is reduced in the high-pressure phase, insulating behavior remains to the highest pressures similar to 1 Mbar. The strongly pressure-dependent insulating gap shows a positive correlation with the expectation value of the angular part of the S-O interaction, < L • S >, which may indicate an active role of S-O interactions in stabilizing the insulating state that emerges in the compressed Na3Ir3O8 structure.},
doi = {10.1103/PhysRevB.98.085131},
journal = {Physical Review B},
number = 8,
volume = 98,
place = {United States},
year = {2018},
month = {8}
}

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