Certain spin Hamiltonians that give rise to tunnel splittings that are viewed in terms of interfering instanton trajectories are restudied using a discrete WKB method, that is more elementary, and also yields wave functions and preexponential factors for the splittings. A novel turning point inside the classically forbidden region is analyzed, and a general formula is obtained for the splittings. The result is applied to the \Fe8 system. A previous result for the oscillation of the ground state splitting with external magnetic field is extended to higher levels.
ASJC Scopus subject areas
- Physics and Astronomy(all)