Portal de Periódicos da CAPES

Theory of magnetic order in the three-dimensional spatially anisotropic Heisenberg model

2000; American Physical Society; Volume: 61; Issue: 21 Linguagem: Inglês

10.1103/physrevb.61.14601

1095-3795

L. Siurakshina, D. Ihle, R. Hayn,

Magnetic properties of thin films

A spin-rotation-invariant Green's-function theory of long- and short-range order (SRO) in the $S=1/2$ antiferromagnetic Heisenberg model with spatially anisotropic couplings on a simple cubic lattice is presented. The staggered magnetization, the two-spin correlation functions, the correlation lengths, and the static spin susceptibility are calculated self-consistently over the whole temperature region, where the effects of spatial anisotropy are explored. As compared with previous spin-wave approaches, the N\'eel temperature is reduced by the improved description of SRO. The maximum in the temperature dependence of the uniform static susceptibility is shifted with anisotropy, and is ascribed to the decrease of SRO with increasing temperature. Comparing the theory with experimental data for the magnetization and correlation length of ${\mathrm{La}}_{2}{\mathrm{CuO}}_{4},$ a good agreement in the temperature dependences is obtained.