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|Title:||Spin glass behavior in frustrated quantum spin system CuAl2O4 with a possible orbital liquid state|
Jang, K. -H.
Yang, N. -G.
Ibberson, R. M.
Cheong, S. -W.
Gapontsev, V. V.
Streltsov, S. V.
Park, J. -G.
|Publisher:||Institute of Physics Publishing|
|Citation:||Spin glass behavior in frustrated quantum spin system CuAl2O4 with a possible orbital liquid state / R. Nirmala, K. -H. Jang, H. Sim, et al. — DOI 10.1088/1361-648X/aa5c72 // Journal of Physics Condensed Matter. — 2017. — Vol. 29. — Iss. 13. — 13LT01.|
|Abstract:||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. On the other hand, 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. Thus, 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. Our observations suggest that CuAl2O4 should be a rare example of a frustrated quantum spin glass with a good candidate for an orbital liquid state. © 2017 IOP Publishing Ltd.|
ORBITAL LIQUID STATE
QUANTUM SPIN SYSTEM
AC MAGNETIC SUSCEPTIBILITY
HIGH RESOLUTION NEUTRON POWDER DIFFRACTION DATA
QUANTUM SPIN SYSTEMS
|Appears in Collections:||Научные публикации, проиндексированные в SCOPUS и WoS CC|
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