Weak-universal critical behavior and quantum critical point of the exactly soluble spin-1/2 Ising-Heisenberg model with the pair XYZ Heisenberg and quartic Ising interactions

摘要

Spin-1/2 Ising-Heisenberg model with XYZ Heisenberg pair interaction and twodifferent Ising quartic interactions is exactly solved with the help of thegeneralized star-square transformation, which establishes a precise mappingequivalence with the corresponding eight-vertex model on a square latticegenerally satisfying Baxter's zero-field (symmetric) condition. Theinvestigated model exhibits a remarkable weak-universal critical behavior withtwo marked wings of critical lines along which critical exponents varycontinuously with the interaction parameters. Both wings of critical linesmerge together at a very special quantum critical point of the infinite order,which can be characterized through diverging critical exponents. Thepossibility of observing reentrant phase transitions in a close vicinity of thequantum critical point is related to a relative strength of the exchangeanisotropy in the XYZ Heisenberg pair interaction.