1p-PS-30 Critical Line of Two-Dimensional Spin-1/2 Pair-Product Heisenberg Model

G. Seto, R. A. A. Yessoufou, A. V. Kpadonou +1 more

T. Onogi, Seiji Miyashita, Masuo Suzuki

A critical line of the pair-product approximant of the two-dimensional spin-1/2 Heisenberg model is obtained exactly in an interaction region, by using the fact that it can be mapped exactly into a staggered eight-vertex model and can be reduced further to a special Baxter model or F model.

J. F. Audet, A. Fledderjohann, C. Gerhardt +3 more

Jozef Strečka, Lucia Čanová, Kazuhiko Minami +4 more

Spin‐1/2 Ising‐Heisenberg model withXYZ Heisenberg pair interaction and two different Ising quartic interactions is exactly solved with the help of the generalized star‐square transformation, which establishes a precise mapping equivalence with the corresponding eight‐vertex model on a square lattice generally satisfying Baxter’s zero‐field (symmetric) condition. The investigated model exhibits a remarkable weak‐universal critical behavior with two marked wings of critical lines along which critical exponents vary continuously with the interaction parameters. Both wings of critical lines merge together at a very special quantum critical point of the infinite order, which can be characterized through diverging critical exponents. The possibility of observing reentrant phase transitions in a close vicinity of the quantum critical point is related to a relative strength of the exchange anisotropy in the XYZ Heisenberg pair interaction.

J. Ricardo de Sousa

Sudhakara Yarlagadda, Susumu Kurihara