中国物理B ›› 2008, Vol. 17 ›› Issue (4): 1436-1442.doi: 10.1088/1674-1056/17/4/048

• CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES • 上一篇    下一篇

Dephasing of quantum tunnelling in molecular nanomagnets

张树群1, 陈芝得2   

  1. (1)Department of Optoelectronic Engineering, Jinan University, Guangzhou 510632, China; (2)Department of Physics, Jinan University, Guangzhou 510632, China
  • 收稿日期:2007-09-14 修回日期:2007-10-14 出版日期:2008-04-20 发布日期:2008-04-20
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No 10575045).

Dephasing of quantum tunnelling in molecular nanomagnets

Zhang Shu-Qun(张树群)a) and Chen Zhi-De(陈芝得)b)†   

  1. a Department of Optoelectronic Engineering, Jinan University, Guangzhou 510632, China; b Department of Physics, Jinan University, Guangzhou 510632, China
  • Received:2007-09-14 Revised:2007-10-14 Online:2008-04-20 Published:2008-04-20
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No 10575045).

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摘要： Dephasing mechanism of quantum tunnelling in molecular magnets has been studied by means of the spin-coherent-state path integral in a mean field approximation. It is found that the fluctuating uncompensated transverse field from the dipolar-dipolar interaction between molecular magnets contributes a random phase to the quantum interference phase. The resulting transition rate is determined by the average tunnel splitting over the random phase. Such a dephasing process leads to the suppression of quenching due to the quantum phase interference, and to the steps due to odd resonances in hysteresis loop survived, which is in good agreement with experimental observations in molecular nanomagnets Fe8 and Mn$_{12}.$

Abstract: Dephasing mechanism of quantum tunnelling in molecular magnets has been studied by means of the spin-coherent-state path integral in a mean field approximation. It is found that the fluctuating uncompensated transverse field from the dipolar-dipolar interaction between molecular magnets contributes a random phase to the quantum interference phase. The resulting transition rate is determined by the average tunnel splitting over the random phase. Such a dephasing process leads to the suppression of quenching due to the quantum phase interference, and to the steps due to odd resonances in hysteresis loop survived, which is in good agreement with experimental observations in molecular nanomagnets Fe8 and Mn$_{12}.$

Key words: single molecule magnet, quantum tunnelling, dephasing

中图分类号:  (Tunneling, traversal time, quantum Zeno dynamics)

  • 03.65.Xp
75.30.Gw (Magnetic anisotropy) 75.30.Kz (Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)) 75.50.Tt (Fine-particle systems; nanocrystalline materials) 75.50.Xx (Molecular magnets)