Field-induced quasi-particle coherence effects in certain small magnets

TL;DR

This paper investigates how magnetic field-induced oscillations in thermodynamic properties of small magnets can reveal quasi-particle coherence, even when direct detection of tunnel splitting is challenging.

Contribution

It introduces a method to infer quasi-particle coherence in small magnets through thermodynamic oscillations induced by magnetic fields.

Findings

Oscillations in thermodynamic quantities depend on field-induced quasi-particle coherence.

The method can detect coherence without directly observing tunnel splitting.

Provides a new approach to study quantum coherence in magnetic systems.

Abstract

Small ferromagnets and anti-ferromagnets with an easy-plane anisotropy have a ground to first excited state (tunnel) splitting which is quasi-periodic in the magnitude of a field applied perpendicular to a principal anisotropy axis. The associated oscillations in thermodynamic quantities might be used to prove the existence of a coherent ground state even when the tunnel splitting itself cannot be directly detected.