Quantum-Classical Phase Transition of Escape rate in Biaxial Spin Particles

TL;DR

This paper investigates the quantum-classical phase transition in the escape rates of biaxial spin particles, revealing a sharp first-order transition and providing detailed phase diagrams based on anisotropy and external magnetic fields.

Contribution

It introduces new effective Hamiltonians with exact spin-coordinate correspondence, improving upon previous approximate models.

Findings

Identifies a sharp first-order phase transition in escape rates.

Provides phase diagrams showing transition dependence on anisotropy and magnetic field.

Demonstrates the effectiveness of the new Hamiltonian approach.

Abstract

The escape rates of the biaxial single domain spin particles with and without an applied magnetic field are investigated. Using the strict potential field description of spin systems developed by Ulyanov and Zaslavskii we obtain new effective Hamiltonians which are considered to be in exact spin-coordinate correspondence unlike the well studied effective Hamiltonians with the approximate correspondence. The sharp first-order transition is found in both cases. The phase diagram of the transitions depending on the anisotropy constant and the external field is also given.