Energy spectrum and transport properties of the two-dimensional t-J model

Abstract

The formation of a ferromagnetically ordered region around a hole in the two-dimensional t-J model is investigated. The energy bands characterized by different values of the z-component of the total spin are analysed. A strong anisotropy of the lower-energy bands is found. For intermediate coupling of additionally included optical phonons, this anisotropy leads to a large polaronic state with an anisotropic envelope oriented along the plane diagonals. In the strong-coupling case the competition between the hole-magnon and the hole-phonon interactions prevents the formation of ferrons. Owing to the large effective mass in both cases, the hole transport takes place via hopping, with preferential jumps along the diagonals in the intermediate-coupling case and isotropic motion in the strong-coupling case.