Spin-1 chain with spin-1/2 excitations in the bulk

TL;DR

This paper introduces a spin-1 chain model with three exactly solvable ground states, revealing low-energy spin-1/2 excitations with small gaps, and explores generalizations to higher spins and dimensions.

Contribution

The paper presents a novel spin-1 chain with exactly solvable ground states and identifies spin-1/2 excitations, advancing understanding of fractionalization in higher spin systems.

Findings

Identified a low-energy spin-1/2 excitation with a small gap.

Demonstrated three exactly solvable ground states including MG and AKLT types.

Explored potential generalizations to higher spins and dimensions.

Abstract

We present a spin-1 chain with a Hamiltonian which has three exactly solvable ground states. Two of these are fully dimerized, analogous to the Majumdar-Ghosh (MG) states of a spin-1/2 chain, while the third is of the Affleck-Kennedy-Lieb-Tasaki (AKLT) type. We use variational and numerical methods to study the low-energy excitations which interpolate between these ground states in different ways. In particular, there is a spin-1/2 excitation which interpolates between the MG and AKLT ground states; this is the lowest excitation of the system and it has a surprisingly small gap. We discuss generalizations of our model of spin fractionalization to higher spin chains and higher dimensions.