Effect of inhomogeneous fields on quenched tunnel splittings in the Fe8 molecular magnet

It is shown that the experimental data on the magnetic field dependent tunnel splitting in the magnetic molecular solid Fe-8 can be accurately described by assuming an inhomogeneous distribution of dipolar magnetic fields and small misalignments of the molecules. The procedure for averaging over these inhomogeneities is developed in light of the fact that the measured quantity is the Landau-Zener-Stuckelberg relaxation rate. The parameters that best fit the data are discussed in relation to other experiments, and the description is compared to that by previous authors.