Numerical study on spin and charge degrees of freedom in one-dimensional t J model

Abstract

We examined the t J and the t t′ J models in one dimension by numerical diagonalization. We introduced and calculated a quantity Q measuring the mixing of the charge and spin degrees of freedom in a wavefunction. In the case of t'/| t|=0, Q for the ground state vanishes in the limit of J/| t|→0, corresponding to the well-known perfect separation of the wave function. As J/| t| increases, Q increases rapidly for small J/| t| and becomes very close to the value of the Gutzwiller wavefunction for J/| t|=2. In the case of finite t′/| t|, Q is finite even if J/| t|=0, showing that the hole motion drived by the second neighbor hopping t′ effectively exchanges electronic spins or mixes the spin and the charge degrees of freedom.