Quantum spin XXZ-type models with Gibbsian ground states and double long-range order

秀稔 西森, Hidetoshi Nishimori, 之康 尾関 +1 more

達也 岸, Tatsuya Kishi

T. C. Dorlas, W. I. Skrypnik

We describe a family of quantum spin models which are generators of a discrete Markovian process. We show that there exists an explicit expression for the ground state of such models and give a simple argument for the existence of two types of long-range order in such systems. Two special examples of these systems are analysed in detail.

W. I. Skrypnik

A class of general spin 1 2 lattice models on hyper-cubic lattice Z d , whose Hamiltonians are sums of two functions depending on the Pauli matrices S 1 , S 2 and S 3 , respectively, are found, which have Gibbsian eigen (ground) states and two order parameters for two spin components x, z simultaneously for large values of the parameter α playing the role of the inverse temperature.It is shown that the ferromagnetic order in x direction exists for all dimensions d ≥ 1 for a wide class of considered models (a proof is remarkably simple).

Qian‐Qian Shi

Chi Shi