Title:
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Evidence for resonant tunneling of magnetization in Mn12 acetate complex
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Author:
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Hernández Ferràs, Joan Manel; Zhang, Xixiang; Luis, F.; Tejada Palacios, Javier; Friedman, Jonathan R.; Sarachik, M. P.; Ziolo, R. F.
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Other authors:
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Universitat de Barcelona |
Abstract:
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We have measured the dc magnetization at low temperatures of tetragonal crystals of Mn12 acetate complex
[Mn12O12[CH3COO]16[H2O]4], a material composed of a large ~Avogadro’s! number of identical magnetic
molecules, each of spin 10. Exchange coupling between Mn ions within each molecule is very strong, while the
interaction between molecules is negligible. A large, uniaxial anisotropy ~;60 K! gives rise to a doubly
degenerate ground state corresponding to spin projections of 610 along the easy axis ~c axis!; hysteretic
behavior is found below a blocking temperature Tb;3 K. Based on measurements of oriented crystallites at
temperatures between 1.7 and 3.2 K, we report strong evidence for resonant tunneling of the magnetization:
periodic steps in the hysteresis loop, and periodic marked increases in the magnetic relaxation rate at the
magnetic fields corresponding to these steps. A total of seven increases in the relaxation rate were found within
the temperature range of our experiments with a period of 0.46 T; we suggest that many more such steps would
be found at lower temperatures. We attribute these observations to thermally assisted resonant tunneling of the
magnetization and propose a detailed model to account for our results. |
Subject(s):
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-Materials magnètics -Propietats magnètiques -Magnetic properties -Magnetic materials |
Rights:
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(c) The American Physical Society, 1997
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Document type:
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Article Article - Published version |
Published by:
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The American Physical Society
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