Non-Kramers freezing and unfreezing of tunneling in the biaxial spin model
Department of Physics and Astronomy, City University of New
Bedford Park Boulevard West, Bronx, New York 10468-1589, USA
2 Departament de Física Fonamental, Universitat de Barcelona Diagonal 647, 08028 Barcelona, Spain
Accepted: 15 February 2000
The ground state tunnel splitting for the biaxial spin model in the magnetic field, , has been investigated using an instanton approach. We find a new type of spin instanton and a new quantum interference phenomenon associated with it: at a certain field, , the dependence of the tunneling splitting on the field switches from oscillations to a monotonic growth. The predictions of the theory can be tested in Fe8 molecular nanomagnets.
PACS: 75.45.+j – Macroscopic quantum phenomena in magnetic systems / 75.50.Xx – Molecular magnets
© EDP Sciences, 2000