Abstract
GeCu2O4 spinel exhibits a tetragonal structure due to the strong Jahn-Teller distortion associated with Cu2+ ions. We show that its magnetic structure can be described as slabs composed of a pair of layers with orthogonally oriented spin-12 Cu chains in the basal ab plane. The spins between the two layers within a slab are collinearly aligned while the spin directions of neighboring slabs are perpendicular to each other. Interestingly, we find that spins along each chain form an unusual up-up-down-down (UUDD) pattern, suggesting a non-negligible nearest-neighbor biquadratic exchange interaction in the effective classical spin Hamiltonian. We hypothesize that spin-orbit coupling and orbital mixing of Cu2+ ions in this system are non-negligible, which calls for future calculations using perturbation theory with extended Hilbert (spin and orbital) space and calculations based on density functional theory including spin-orbit coupling and looking at the global stability of the UUDD state.
Original language | English |
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Article number | 214406 |
Journal | Physical Review B |
Volume | 94 |
Issue number | 21 |
DOIs | |
State | Published - Dec 7 2016 |
Funding
Work at Michigan State University was supported by the start-up funds from Michigan State University and by the National Science Foundation under Award No. DMR-1608752. J.G.C. acknowledges the support of the NNSF and MOST of China (Grants No. 11304371, No. 11574377, and No. 2014CB921500), the Strategic Priority Research Program and the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences (Grant No. XDB07020100), and the Opening Project of Wuhan National High Magnetic Field Center (Grant No. 2015KF22), Huazhong University of Science and Technology. Work at ORNL was supported by the Scientific User Facilities Division, Office of Basic Energy Sciences, DOE.