beta-Cu2V2O7: a spin-1-2 honeycomb lattice system - Condensed Matter > Strongly Correlated ElectronsReportar como inadecuado




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Abstract: We report on band structure calculations and a microscopic model of thelow-dimensional magnet beta-Cu2V2O7. Magnetic properties of this compound canbe described by a spin-1-2 anisotropic honeycomb lattice model with theaveraged coupling \bar J1=60-66 K. The low symmetry of the crystal structureleads to two inequivalent couplings J1 and J1-, but this weak spatialanisotropy does not affect the essential physics of the honeycomb spin lattice.The structural realization of the honeycomb lattice is highly non-trivial: theleading interactions J1 and J1- run via double bridges of VO4 tetrahedrabetween spatially separated Cu atoms, while the interactions between structuralnearest neighbors are negligible. The non-negligible inter-plane couplingJperp~15 K gives rise to the long-range magnetic ordering at TN~26 K. Our modelsimulations improve the fit of the magnetic susceptibility data, compared tothe previously assumed spin-chain models. Additionally, the simulated orderingtemperature of 27 K is in remarkable agreement with the experiment. Our studyevaluates beta-Cu2V2O7 as the best available experimental realization of thespin-1-2 Heisenberg model on the honeycomb lattice. We also provide aninstructive comparison of different band structure codes and computationalapproaches to the evaluation of exchange couplings in magnetic insulators.



Autor: Alexander A. Tsirlin, Oleg Janson, Helge Rosner

Fuente: https://arxiv.org/







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