Spin excitations and thermodynamics of the antiferromagnetic Heisenberg model on the layered honeycomb lattice
1 Joint Institute for Nuclear Research, 141980 Dubna, Russia
2 Institut für Theoretische Physik, Universität Leipzig, 04109 Leipzig, Germany
3 Max-Planck-Institut für Physik Komplexer Systeme, 01187 Dresden, Germany
Received: 7 December 2016
Received in final form: 30 January 2017
Published online: 15 March 2017
We present a spin-rotation-invariant Green-function theory for the dynamic spin susceptibility in the spin-1/2 antiferromagnetic Heisenberg model on a stacked honeycomb lattice. Employing a generalized mean-field approximation for arbitrary temperatures, the thermodynamic quantities (two-spin correlation functions, internal energy, magnetic susceptibility, staggered magnetization, Néel temperature, correlation length) and the spin-excitation spectrum are calculated by solving a coupled system of self-consistency equations for the correlation functions. The temperature dependence of the magnetic (uniform static) susceptibility is ascribed to antiferromagnetic short-range order. The Néel temperature is calculated for arbitrary interlayer couplings. Our results are in a good agreement with numerical computations for finite clusters and with available experimental data on the β-Cu2V2O2 compound.
Key words: Solid State and Materials
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