Distribution of tunnel splittings in Mn(12) acetate.
In magnetic fields applied parallel to the anisotropy axis, the relaxation of the magnetization of Mn(12)-acetate measured for different sweep rates collapses onto a single scaled curve. The form of the scaling implies that the dominant symmetry-breaking process responsible for tunneling is a locally varying second-order transverse anisotropy, forbidden by tetragonal symmetry in the perfect crystal, which gives rise to a broad distribution of tunnel splittings in a real crystal of Mn(12) acetate. Different forms applied to even- and odd-numbered steps provide a clear distinction between even resonances (associated with crystal anisotropy) and odd resonances (which require a transverse magnetic field).
Mertes
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KM
Physics Department, City College of the City University of New York, New York, New York 10031, USA.
Suzuki
Y
Y
Sarachik
M P
MP
Paltiel
Y
Y
Shtrikman
H
H
Zeldov
E
E
Rumberger
E
E
Hendrickson
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DN
Christou
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G