Effects of arbitrarily directed field on quantum phase interference in biaxial ferrimagnetic particles

The tunneling splitting in biaxial ferrimagnetic particles is obtained as a function of magnetic field applied along an arbitrary direction in the pla ne of hard and medium axes. We observe the oscillation of tunnel splitting with respect to the magnitude and the direction of the magnetic field due t o the quantum phase interference of two tunneling paths of opposite winding s. The oscillation is gradually smeared and in the end the tunnel splitting monotonously increases with the magnitude of the magnetic held when the di rection of the magnetic field tends to the medium axis, The behavior of the tunnel splitting as a function of magnetic field is similar to the recent experimental observation with Feb: molecular clusters. (C) 2001 Published b y Elsevier Science B.V.