title: Definitive spectroscopic determination of the transverse interactions responsible for the magnetic quantum tunneling in Mn(12)-acetate.
abstract: We present detailed angle-dependent single crystal electron paramagnetic resonance (EPR) data for field rotations in the hard plane of the S=10 single molecule magnet Mn(12)-acetate. A clear fourfold variation in the resonance positions may be attributed to an intrinsic fourth-order transverse anisotropy (O(4)/(4)). Meanwhile, a fourfold variation of the EPR line shapes confirms a recently proposed model wherein disorder associated with the acetic acid of crystallization induces a locally varying quadratic (rhombic) transverse anisotropy [O (2)/(2) identical with E(S (2)/(x)-S(2)/(y))]. These findings explain most aspects of the magnetic quantum tunneling observed in Mn(12)-acetate.
authors.affiliation: Department of Physics, University of Florida, Gainesville, Florida 32611, USA.
authors.forename: S
authors.initials: S
authors.lastname: Hill
authors.forename: R S
authors.initials: RS
authors.lastname: Edwards
authors.forename: S I
authors.initials: SI
authors.lastname: Jones
authors.forename: N S
authors.initials: NS
authors.lastname: Dalal
authors.forename: J M
authors.initials: JM
authors.lastname: North