Spin tunneling properties in mesoscopic magnets: effects of a magnetic field |
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Authors: | R Lü H Pan J-L Zhu B-L Gu |
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Institution: | (1) Center for Advanced Study, Tsinghua University, Beijing 100084, PR China, CN |
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Abstract: | The tunneling of a giant spin at excited levels is studied theoretically in mesoscopic magnets with a magnetic field at an
arbitrary angle in the easy plane. Different structures of the tunneling barriers can be generated by the magnetocrystalline
anisotropy, the magnitude and the orientation of the field. By calculating the nonvacuum instanton solution explicitly, we
obtain the tunnel splittings and the tunneling rates for different angle ranges of the external magnetic field ( θ
H = π/2 and π/2 < θ
H < π). The temperature dependences of the decay rates are clearly shown for each case. It is found that the tunneling rate
and the crossover temperature depend on the orientation of the external magnetic field. This feature can be tested with the
use of existing experimental techniques.
Received 12 March 2001 and Received in final form 18 October 2001 |
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Keywords: | PACS 75 45 +j Macroscopic quantum phenomena in magnetic systems – 75 50 Mm Magnetic liquids |
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