Enhancement of Quantum Tunneling for Excited States in Ferromagnetic Particles

TL;DR

This paper derives a formula using the instanton method to evaluate quantum tunneling in ferromagnetic particles, revealing increased tunneling at excited states, aiding experimental analysis of macroscopic quantum coherence.

Contribution

It introduces a new formula based on the instanton method to quantify tunneling effects at excited states in ferromagnetic particles, enhancing previous theoretical approaches.

Findings

Tunneling effect increases at excited states.

Derived a formula for tunneling using instanton method.

Results aid in analyzing experimental quantum coherence tests.

Abstract

A formula suitable for a quantitative evaluation of the tunneling effect in a ferromagnetic particle is derived with the help of the instanton method. The tunneling between n-th degenerate states of neighboring wells is dominated by a periodic pseudoparticle configuration. The low-lying level-splitting previously obtained with the LSZ method in field theory in which the tunneling is viewed as the transition of n bosons induced by the usual (vacuum) instanton is recovered. The observation made with our new result is that the tunneling effect increases at excited states. The results should be useful in analyzing results of experimental tests of macroscopic quantum coherence in ferromagnetic particles.