Oscillation of the tunnel splitting in nanospin systems within the particle mapping formalism

TL;DR

This paper investigates the oscillation of tunnel splitting in biaxial nanospin systems using a particle mapping approach, revealing a topological phase analogous to the Wess-Zumino action and confirming tunneling quenching conditions.

Contribution

It introduces a novel particle mapping formalism for analyzing tunnel splitting oscillations, providing an alternative to the spin coherent-state representation.

Findings

Derived a new topological phase similar to Wess-Zumino action.

Confirmed the tunneling quenching condition matches previous results.

Established the validity of the particle mapping approach for spin systems.

Abstract

The oscillation of tunnel splitting in the biaxial spin system within magnetic field along the anisotropy axis is analyzed within the particle mapping approach, rather than in the (\theta-\phi) spin coherent-state representation. In our mapping procedure, the spin system is transformed into a particle moving in the restricted $S^1$ geometry whose wave function subjects to the boundary condition involving additional phase shift. We obtain the new topological phase that plays the same role as the Wess-Zumino action in spin coherent-state representation. Considering the interference of two possible trajectories, instanton and anti-instanton, we get the identical condition for the field at which tunneling is quenched, with the previous result within spin coherent-state representation.