Temperature dependence of sublattice magnetization in quasi-two-dimensional S =1/2 cuprate antiferromagnets: Green's function approach

摘要

The study of temperature dependence of the sublattice magnetization in the quasi-two-dimensional S = 1/2 cuprate antiferromagnets was inspired by the existing experimental evidence concerning sublattice magnetization temperature dependence, both in the vicinity of absolute zero for the high-T_C parent compound La_2Cu0_4 and in the whole temperature region from absolute zero to the Neel temperature (T_N) for La_2CuO_4 and YBa_2Cu_3O_(6.15) Using the spin Green's functions method for the quantum Heisenberg antiferromagnetic model, we obtain the results which show excellent agreement with the experimental data, proving that in the wide temperature region (from 0 to T_N), this method is more appropriate than the harmonic spin-wave theory and Schwinger-boson mean-field theory.