Incommensurate transverse anisotropy induced by disorder and spin-orbit-vibron coupling in Mn12 acetate

It has been shown within density-functional theory that in Mn12 acetate there are effects due to disorder by solvent molecules and a coupling between vibrational and electronic degrees of freedom. We calculate the in-plane principal axes of the second-order anisotropy caused by the second effect and compare them with those of the fourth-order anisotropy due to the first effect. We find that the two types of the principal axes are not commensurate with each other, which results in a complete quenching of the tunnel-splitting oscillation as a function of an applied transverse field.

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