Metamagnetic phase transition of the antiferromagnetic Heisenberg icosahedron

TL;DR

This paper demonstrates a first-order metamagnetic phase transition in a geometrically frustrated antiferromagnetic Heisenberg icosahedron, showing hysteresis effects without magnetic anisotropy, driven by geometric frustration.

Contribution

It reveals a novel hysteresis phenomenon and phase transition in a symmetric spin system, expanding understanding of magnetic behavior beyond anisotropic materials.

Findings

Hysteresis occurs in an isotropic spin system due to geometric frustration.

A first-order phase transition is observed at zero temperature.

Metastable states depend on temperature and magnetic field.

Abstract

The observation of hysteresis effects in single molecule magnets like Mn$_{12}$-acetate has initiated ideas of future applications in storage technology. The appearance of a hysteresis loop in such compounds is an outcome of their magnetic anisotropy. In this Letter we report that magnetic hysteresis occurs in a spin system without any anisotropy, specifically, where spins mounted on the vertices of an icosahedron are coupled by antiferromagnetic isotropic nearest-neighbor Heisenberg interaction giving rise to geometric frustration. At T=0 this system undergoes a first order metamagnetic phase transition at a critical field $\Bcrit$ between two distinct families of ground state configurations. The metastable phase of the system is characterized by a temperature and field dependent survival probability distribution.