Exchange distortion and spin Jahn-Teller effect for triangular and tetrahedral spin clusters of spin-1/2

TL;DR

This paper investigates how magneto-elastic coupling influences the ground state degeneracy in spin-1/2 clusters, revealing that static distortions lift degeneracy while dynamic ones do not, with implications for spinel phase transitions.

Contribution

It provides a comparative analysis of static versus dynamic distortions on ground state degeneracy in triangular and tetrahedral spin clusters.

Findings

Static distortion lifts ground state degeneracy.

Quantum-mechanical distortion does not lift degeneracy.

Discussion of tetragonal distortion at spinel phase transition.

Abstract

We study the effects of magneto-elastic coupling on the degenerate ground state of the antiferromagnetic Heisenberg model on regular triangle and tetrahedron clusters of spin-1/2. Both give very similar results. Static distortion lifts the degeneracy of the ground state through the distance dependence of the exchange coupling. On the contrary, quantum-mechanical or dynamical distortion does not. The tetragonal distortion at the non-magnetic phase transition of spinels is discussed.