Evidence for Spin-Charge Separation in the Two-Dimensional T-J Model

TL;DR

This study uses high temperature expansions to analyze the two-dimensional t-J model, providing evidence for spin-charge separation through characteristic features in momentum distribution and correlation functions.

Contribution

It offers the first evidence of spin-charge separation in the 2D t-J model based on high temperature expansion extrapolations.

Findings

Step-like feature in $n_{\bf k}$ at ${\bf k}_F$

Characteristic wavevector $2{\bf k}_F$ in $S({\bf q})$

Characteristic wavevector $2{\bf k}_F^{SF}$ in $N({\bf q})$

Abstract

We have calculated high temperature expansions for the momentum distribution function $n_{\scriptscriptstyle\bf k}$ and the equal time spin and density correlation functions $S({\bf q})$ and $N({\bf q})$ of the two-dimensional $t$-$J$ model. On extrapolation to low temperatures we find that $n_{\scriptscriptstyle\bf k}$ has a step-like feature at ${\bf k}_{\scriptscriptstyle F}$ and $S({\bf q})$ has $2{\bf k}_{\scriptscriptstyle F}$ as a characteristic wavevector, whereas $N({\bf q})$ has $2{\bf k}_{\scriptscriptstyle F}^{\scriptscriptstyle SF}$ as a characteristic wavevector. Here ${\bf k}_{\scriptscriptstyle F}$ and ${\bf k}_{\scriptscriptstyle F}^{\scriptscriptstyle SF}$ are the Fermi wavevectors of the nearest-neighbor square lattice tight-binding and spinless fermion models, respectively. By comparison to the known results for one dimension this suggests spin-charge separation in the two-dimensional $t$-$J$ model.