Local three-spin correlations in the free-fermion and

Robert A. Close

Ken‐Yu Lin, Fa Yueh Wu

The authors consider the free-fermion model on the square lattice and obtain the local three-spin correlation function for three spins surrounding a unit cell of the lattice. As an application of this result, they compute the spontaneous magnetisation for the Ising model on the Union Jack lattice with the most general anisotropic interactions.

Rakhal Deviprasad Dave

R. J. Baxter, T. C. Choy

Abstract A number of local three-spin correlations are calculated exactly for various related ferromagnetic two-dimensional solvable models in statistical mechanics.They are the square lattice free-fermion model, the equivalent checkerboard Ising model, and the anisotropic triangular, honeycomb and square lattice Ising models. The different results are all applications of a single unifying formula.

J. Rae

Fabian H. L. Eßler, Rianne van den Berg, Vladimir Gritsev

We study a Yang-Baxter integrable quantum spin-1/2 chain with random interactions. The Hamiltonian is local and involves two- and three-spin interactions with random parameters. We show that the energy eigenstates of the model are never localized and in fact exhibit perfect energy and spin transport at both zero and infinite temperatures. By considering the vicinity of a free fermion point in the model we demonstrate that this behavior persists under deformations that break Yang-Baxter integrability but preserve the free fermion nature of the Hamiltonian. In this case the ballistic behavior can be understood as arising from the correlated nature of the disorder in the model. We conjecture that the model belongs to a broad class of models avoiding localization in 1D.