Journal of the Physical Society of Japan
Thermodynamic Properties of the One-Dimensional Spin-1/2 Heisenberg Antiferromagnet with Competing Interactions
Isao Harada, Tetsuji Kimura, Takashi Tonegawa
Abstract
Thermodynamic properties are studied for the one-dimensional spin-1/2 Heisenberg antiferromagnet with antiferromagnetic first- and second-neighbor exchange interactions. The internal energy, the specific heat, and the two-spin correlation function are calculated by means of the cluster transfer matrix method based on the Suzuki-Trotter equivalence theorem. Special attention is paid to the asymptotic behavior of the two-spin correlation function in the long-distarace limit. It is found that for a certain range of values of the interaction constants and of the temperature, the two-spin correlation function decays with an incommensurate or a higher-order commensurate oscillation as a function of the distance between two spins. We also find that there exists a quantum analog of the disorder line, on which the two-spin correlation function changes its character.