Phase transition between quantum and classical regimes for the escape rate of a biaxial spin system

Abstract

Employing the method of mapping the spin problem onto a particle one, we have derived the particle Hamiltonian for a biaxial spin system with a transverse or longitudinal magnetic field. Using the Hamiltonian and introducing the parameter $p(\equiv (U_{max}-E)/(U_{max}-U_{min}))$ where $U_{max}$ (U_{min}) corresponds to the top (bottom) of the potential and $E$ is the energy of the particle, we have studied the first- or second-order transition around the crossover temperature between thermal and quantum regimes for the escape rate, depending on the anisotropy constant and the external magnetic field. It is shown that the phase boundary separating the first- and second-order transition and its crossover temperature are greatly influenced by the transverse anisotropy constant as well as the transverse or longitudinal magnetic field.

5 pages + 3 figures, to be published in Phys. Rev. B

References in corpus (6)

• Thermally Activated Resonant Magnetization Tunneling in Molecular Magnets: Mn_12Ac and others
• First- and Second-Order Transitions between Quantum and Classical Regimes for the Escape Rate of a Spin System
• Quantum-Classical Transition of the Escape Rate of a Uniaxial Spin System in an Arbitrarily Directed Field
• Periodic Instantons and Quantum-Classical Transitions in Spin Systems
• Quantum-Classical Escape-Rate Transition of a Biaxial Spin System with a Longitudinal Field: a Perturbative Approach
• Quantum Tunneling and Phase Transitions in Spin Systems with an Applied Magnetic Field

Cited by in corpus (8)

• Resonant Tunneling in Truly Axial Symmetry Mn12 Single-Molecule Magnets: Sharp Crossover between Thermally Assisted and Pure Quantum Tunneling
• Macroscopic quantum tunneling and quantum-classical phase transitions of the escape rate in large spin systems
• Escape-Rate Crossover between Quantum and Classical Regimes in Molecular Magnets: A Diagonalization Approach
• First- and second-order transitions of the escape rate in ferrimagnetic or antiferromagnetic particles
• Macroscopic quantum effects generated by the acoustic wave in a molecular magnet
• Phase transition between quantum and classical regimes for the escape rate of dimeric molecular nanomagnets in a staggered magnetic field
• Quantum-classical phase transition of the escape rate of two-sublattice antiferromagnetic large spins
• Quantum-classical transition of the escape rate of a biaxial ferromagnetic spin with an external magnetic field