Exact spin-orbital separation in a solvable model in one dimension

TL;DR

This paper rigorously demonstrates exact spin-orbital separation in a one-dimensional coupled spin-pseudospin model using a non-local unitary transformation, revealing decoupled spin and orbital behaviors.

Contribution

It provides an exact solution for spin-orbital separation in a 1D model, including a transformation that decouples spins from orbitals and discusses generalizations.

Findings

Spins become paramagnetic after transformation

Orbitals form a solvable XXZ Heisenberg model

Method applies to broader spin-orbital systems

Abstract

A one-dimensional model of coupled spin-1/2 spins and pseudospin-1/2 orbitals with nearest-neighbor interaction is rigorously shown to exhibit spin-orbital separation by means of a non-local unitary transformation. On an open chain, this transformation completely decouples the spins from the orbitals in such a way that the spins become paramagnetic while the orbitals form the soluble XXZ Heisenberg model. The nature of various correlations is discussed. The more general cases, which allow spin-orbital separation by the same method, are pointed out. A generalization for the orbital pseudospin greater than 1/2 is also discussed. Some qualitative connections are drawn with the recently observed spin-orbital separation in Sr2CuO3.