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Title: Spin glass behavior in frustrated quantum spin system CuAl 2 O 4 with a possible orbital liquid state

Abstract

CuAl 2O 4 is a normal spinel oxide having quantum spin, S = 1/2 for Cu 2+. It is a rather unique feature that the Cu 2+ ions of CuAl 2O 4 sit at a tetrahedral position, not like the usual octahedral position for many oxides. At low temperatures, it exhibits all the thermodynamic evidence of a quantum spin glass. For example, the polycrystalline CuAl 2O 4 shows a cusp centered at ~2 K in the low-field dc magnetization data and a clear frequency dependence in the ac magnetic susceptibility while it displays logarithmic relaxation behavior in a time dependence of the magnetization. At the same time, there is a peak at ~2.3 K in the heat capacity, which shifts towards a higher temperature with magnetic fields. Conversely, there is no evidence of new superlattice peaks in the high-resolution neutron powder diffraction data when cooled from 40 to 0.4 K. This implies that there is no long-ranged magnetic order down to 0.4 K, thus confirming a spin glass-like ground state for CuAl 2O 4. Interestingly, there is no sign of structural distortion either although Cu 2+ is a Jahn–Teller active ion. Therefore, we claim that an orbital liquid state ismore » the most likely ground state in CuAl 2O 4. Of further interest, it also exhibits a large frustration parameter, f = |θ CW/T m| ~ 67, one of the largest values reported for spinel oxides. These observations suggest that CuAl 2O 4 should be a rare example of a frustrated quantum spin glass with a good candidate for an orbital liquid state.« less

Authors:
 [1];  [2];  [3];  [3];  [2];  [2];  [4];  [5];  [6];  [7];  [8];  [9];  [10];  [11]
  1. Seoul National Univ. (Korea, Republic of). Center for Stronly Correlated Materials Research; Indian Inst. of Technology (IIT), Madras (India). Dept. of Physics; Sungkyunkwan Univ., Suwon (Republic of Korea). Dept. of Physics
  2. Seoul National Univ. (Korea, Republic of). Center for Stronly Correlated Materials Research; Sungkyunkwan Univ., Suwon (Republic of Korea). Dept. of Physics
  3. Inst. for Basic Science, Seoul (Korea, Republic of). Center for Correlated Electron Systems; Seoul National Univ. (Korea, Republic of). Dept. of Physics and Astronomy
  4. Korea Atomic Energy Research Inst., Daejeon (Korea, Republic of). Neturon Science Division; Rutgers Univ., Piscataway, NJ (United States). Rutgers Center for Emergent Materials and Dept. of Physics and Astronomy
  5. ISIS Facility, Didcot (United Kingdom). Rutherford Appleton Lab.; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical and Engineering Materials
  6. Japan Atomic Energy Agency (JAEA), Tokai (Japan). Quantum Beam Science Center
  7. Japan Atomic Energy Agency (JAEA), Tokai (Japan). Quantum Beam Science Center; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Quantum Condensed Matter Division
  8. Rutgers Univ., Piscataway, NJ (United States). Rutgers Center for Emergent Materials and Dept. of Physics and Astronomy
  9. Russian Academy of Sciences (RAS), Ekaterinburg (Russian Federation). MN Miheev Inst. of Metal Physics of Ural Branch
  10. Russian Academy of Sciences (RAS), Ekaterinburg (Russian Federation). MN Miheev Inst. of Metal Physics of Ural Branch; Ural Federal Univ., Ekaterinburg (Russia)
  11. Seoul National Univ. (Korea, Republic of). Center for Stronly Correlated Materials Research; Sungkyunkwan Univ., Suwon (Republic of Korea). Dept. of Physics; Inst. for Basic Science, Seoul (Korea, Republic of). Center for Correlated Electron Systems; Seoul National Univ. (Korea, Republic of). Dept. of Physics and Astronomy
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1346686
Grant/Contract Number:  
AC05-00OR22725; FG02-07ER46382
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Physics. Condensed Matter
Additional Journal Information:
Journal Volume: 29; Journal Issue: 13; Journal ID: ISSN 0953-8984
Publisher:
IOP Publishing
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; quantum spin system; frustration; spin glass; orbital liquid state

Citation Formats

Nirmala, R., Jang, Kwang-Hyun, Sim, Hasung, Cho, Hwanbeom, Lee, Junghwan, Yang, Nam-Geun, Lee, Seongsu, Ibberson, R. M., Kakurai, K., Matsuda, M., Cheong, S-W, Gapontsev, V. V., Streltsov, S. V., and Park, Je-Geun. Spin glass behavior in frustrated quantum spin system CuAl 2 O 4 with a possible orbital liquid state. United States: N. p., 2017. Web. doi:10.1088/1361-648X/aa5c72.
Nirmala, R., Jang, Kwang-Hyun, Sim, Hasung, Cho, Hwanbeom, Lee, Junghwan, Yang, Nam-Geun, Lee, Seongsu, Ibberson, R. M., Kakurai, K., Matsuda, M., Cheong, S-W, Gapontsev, V. V., Streltsov, S. V., & Park, Je-Geun. Spin glass behavior in frustrated quantum spin system CuAl 2 O 4 with a possible orbital liquid state. United States. doi:10.1088/1361-648X/aa5c72.
Nirmala, R., Jang, Kwang-Hyun, Sim, Hasung, Cho, Hwanbeom, Lee, Junghwan, Yang, Nam-Geun, Lee, Seongsu, Ibberson, R. M., Kakurai, K., Matsuda, M., Cheong, S-W, Gapontsev, V. V., Streltsov, S. V., and Park, Je-Geun. Wed . "Spin glass behavior in frustrated quantum spin system CuAl 2 O 4 with a possible orbital liquid state". United States. doi:10.1088/1361-648X/aa5c72. https://www.osti.gov/servlets/purl/1346686.
@article{osti_1346686,
title = {Spin glass behavior in frustrated quantum spin system CuAl 2 O 4 with a possible orbital liquid state},
author = {Nirmala, R. and Jang, Kwang-Hyun and Sim, Hasung and Cho, Hwanbeom and Lee, Junghwan and Yang, Nam-Geun and Lee, Seongsu and Ibberson, R. M. and Kakurai, K. and Matsuda, M. and Cheong, S-W and Gapontsev, V. V. and Streltsov, S. V. and Park, Je-Geun},
abstractNote = {CuAl2O4 is a normal spinel oxide having quantum spin, S = 1/2 for Cu2+. It is a rather unique feature that the Cu2+ ions of CuAl2O4 sit at a tetrahedral position, not like the usual octahedral position for many oxides. At low temperatures, it exhibits all the thermodynamic evidence of a quantum spin glass. For example, the polycrystalline CuAl2O4 shows a cusp centered at ~2 K in the low-field dc magnetization data and a clear frequency dependence in the ac magnetic susceptibility while it displays logarithmic relaxation behavior in a time dependence of the magnetization. At the same time, there is a peak at ~2.3 K in the heat capacity, which shifts towards a higher temperature with magnetic fields. Conversely, there is no evidence of new superlattice peaks in the high-resolution neutron powder diffraction data when cooled from 40 to 0.4 K. This implies that there is no long-ranged magnetic order down to 0.4 K, thus confirming a spin glass-like ground state for CuAl2O4. Interestingly, there is no sign of structural distortion either although Cu2+ is a Jahn–Teller active ion. Therefore, we claim that an orbital liquid state is the most likely ground state in CuAl2O4. Of further interest, it also exhibits a large frustration parameter, f = |θ CW/T m| ~ 67, one of the largest values reported for spinel oxides. These observations suggest that CuAl2O4 should be a rare example of a frustrated quantum spin glass with a good candidate for an orbital liquid state.},
doi = {10.1088/1361-648X/aa5c72},
journal = {Journal of Physics. Condensed Matter},
number = 13,
volume = 29,
place = {United States},
year = {Wed Feb 15 00:00:00 EST 2017},
month = {Wed Feb 15 00:00:00 EST 2017}
}

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