Quantum Tunneling in Half-Integer Spin Systems

Abstract

Motivated by the experimental observations of resonant tunnelings in the systems with half-integer spin, such as V${}_{15}$ and Mn${}_4$, we study the mechanism of adiabatic change of the magnetization in systems with the time-reversal symmetry. Within the time-reversal symmetric models, effects of several types of perturbations are investigated. Although tunneling between the ground states is suppressed in a simple Kramers doublet, we show that the nonadiabatic transition governed by the Landau-Zener-Stückelberg mechanism occurs in many cases due to the additional degeneracy of the ground state. We also found more general cases where LZS mechanism can not be applied directly even the system shows a kind of adiabatic change of the magnetization.

Cited by in corpus (13)

• Parity Effects in Spin Decoherence
• Integrable time-dependent quantum Hamiltonians
• Hysteresis loops and adiabatic Landau-Zener-Stückelberg transitions in the magnetic molecule V${}_6$
• Magnetic Anisotropy in the Molecular Complex V15
• Multistate Landau-Zener models with all levels crossing at one point
• Magnetic energy-level diagrams of high-spin (Mn${}_{12}$-acetate) and low-spin (V${}_{15}$) molecules
• Dynamic spin localization and gamma-magnets
• Temperature dependence of ESR intensity for the nanoscale molecular magnet V15
• Integrable multistate Landau-Zener models with parallel energy levels
• Dzyaloshinsky-Moriya interaction and long life time of the spin state in the Cu${}_3$ triangular spin cluster by inelastic neutron scattering measurements
• The ESR intensity and the Dzyaloshinsky-Moriya interaction of the nanoscale molecular magnet V15
• A short guide to topological terms in the effective theories of condensed matter
• Quantum response to time-dependent external fields