中国物理B ›› 1999, Vol. 8 ›› Issue (7): 485-489.doi: 10.1088/1004-423X/8/7/002

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CROSSOVER FROM THERMAL HOPPING TO QUANTUM TUNNELING IN FERROMAGNETIC PARTICLE

王小兵1, 蒲富恪2, 寇谡鹏3, 梁九卿3, 张云波3   

  1. (1)Center for Advanced Study, Tsinghua University, Beijing 100084, China; (2)Institute of Physics and Center for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100080, China; Department of Physics, Guangzhou Normal College, Guangzhou 510400, China; (3)Institute of Physics and Center for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100080, China; Department of Physics, Shanxi University, Shanxi 030006, China
  • 收稿日期:1998-11-03 出版日期:1999-07-15 发布日期:1999-07-20
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 19677101 and 19775033.

CROSSOVER FROM THERMAL HOPPING TO QUANTUM TUNNELING IN FERROMAGNETIC PARTICLE

Kou Su-peng (寇谡鹏)ab, Liang Jiu-qing (梁九卿)ab, Zhang Yun-bo (张云波)ab, Wang Xiao-bing (王小兵)c, Pu Fu-ke (蒲富恪)ad   

  1. a Institute of Physics and Center for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100080, China;  b Department of Physics, Shanxi University, Shanxi 030006, China;   c Center for Advanced Study, Tsinghua University, Beijing 100084, China;  d Department of Physics, Guangzhou Normal College, Guangzhou 510400, China
  • Received:1998-11-03 Online:1999-07-15 Published:1999-07-20
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 19677101 and 19775033.

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摘要： The crossover from thermal hopping to quantum tunneling is studied. We show that the decay rate Γ with dissipation can accurately be determined near the crossover temperature. Besides considering the Wentzel-Kramers-Brillo uin exponent, we also calculate contribution of the fluctuation modes around the saddle point and give an extended account of a previous study of crossover region. We deal with two dangerous fluctuation modes whose contribution cannot be calculated by the steepest descent method and show that higher order couplings between the two dangerous modes need to be taken into consideration.

Abstract: The crossover from thermal hopping to quantum tunneling is studied. We show that the decay rate $\varGamma$ with dissipation can accurately be determined near the crossover temperature. Besides considering the Wentzel-Kramers-Brillo uin exponent, we also calculate contribution of the fluctuation modes around the saddle point and give an extended account of a previous study of crossover region. We deal with two dangerous fluctuation modes whose contribution cannot be calculated by the steepest descent method and show that higher order couplings between the two dangerous modes need to be taken into consideration.

中图分类号:  (Fine-particle systems; nanocrystalline materials)

  • 75.50.Tt
75.10.Jm (Quantized spin models, including quantum spin frustration) 75.45.+j (Macroscopic quantum phenomena in magnetic systems)