Bound state of two holes in the t-J model

Abstract

Ground-state properties of two holes in the antiferromagnetic state are studied using t− J model and a variational method where the Hilbert space is restricted. It is shown that two holes are bound to each other for realistic parameter values and the average distance between the two holes is 1.7 a ∼ 1.8 a, where a is a lattice constant. The static spin correlation function S zz ( Q) shows a broad peak around Q = ( π/2, π/2) which originates from the motion of holes. An effective Hamiltonian for quasi-particles is discussed.