ENHANCEMENT OF QUANTUM TUNNELING FOR EXCITED-STATES IN FERROMAGNETIC PARTICLES

A formula suitable for a quantitative evaluation of the tunneling effe ct in a ferromagnetic particle is derived with the help of the instant on method. The tunneling between nth degenerate states of neighboring wells is dominated by a periodic pseudoparticle configuration. The low -lying level-splitting previously obtained with the Lehmann-Symanzik-Z immermann method in field theory in which the tunneling is viewed as t he transition of n bosons induced by the usual (vacuum) instanton is r ecovered. The observation made with our result is that the tunneling e ffect increases at excited states. The results should be useful in ana lyzing results of experimental tests of macroscopic quantum coherence in ferromagnetic particles.