Quantum nucleation in a single-chain magnet.
The field sweep rate (upsilon = dH/dt) and temperature (T) dependence of the magnetization reversal of a single-chain magnet is studied at low temperatures. As expected for a thermally activated process, the nucleation field (H(n)) increases with decreasing T and increasing upsilon. The set of H(n)(T,upsilon) data is analyzed with a model of thermally activated nucleation of magnetization reversal. Below 1 K, H(n) becomes temperature independent but remains strongly sweep rate dependent. In this temperature range, the reversal of the magnetization is induced by a quantum nucleation of a domain wall that then propagates due to the applied field.
Wernsdorfer
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Laboratoire L. Néel, associé à l'UJF, CNRS, BP 166, 38042 Grenoble Cedex 9, France.
Clérac
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Coulon
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Lecren
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Miyasaka
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