Journal of the Physical Society of Japan
Critical Exponents of the Ground State Phase Transitions of the Spin 1/2 Ferromagnetic-Antiferromagnetic Alternating Heisenberg Chain with Anisotropy
Kazuo Hida
Abstract
The critical exponents of the phase transitions in the ground state of the ferromagnetic-antiferromagnetic alternating spin-1/2 Heisenberg chain are determined by means of the numerical diagonalization with emphasis on the boundary between the Haldane phase and the large- D phase. It is found that this phase boundary is a line of continuously varying critical exponents. The results are in agreement with the series expansion results by Yamanaka, Hatsugai and Kohmoto.