中国物理B ›› 2008, Vol. 17 ›› Issue (10): 3894-3901.doi: 10.1088/1674-1056/17/10/056

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Magnon energy gap in a four-layer ferromagnetic superlattice

张志东1, 宋攀攀2, 郭连权2, 邱荣科3   

  1. (1)Shenyang National Laboratory for Materials Science, Institute of Metal Research and International Centre for Materials Physics, Chinese Academy of Sciences, Shenyang { rm 110016, China; (2)Shenyang University of Technology, Shenyang { rm 110023, China; (3)Shenyang University of Technology, Shenyang { rm 110023, China;Shenyang National Laboratory for Materials Science, Institute of Metal Research and International Centre for Materials Physics, Chinese Academy of Sciences, Shenyang { rm 110016, China
  • 收稿日期:2008-04-11 修回日期:2008-05-12 出版日期:2008-10-20 发布日期:2008-10-20
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos 50331030, 10674139 and 10274087), and the Natural Science Foundation of Liaoning Province, China (Grant No 20062040).

Magnon energy gap in a four-layer ferromagnetic superlattice

Qiu Rong-Ke(邱荣科)a)b)†, Song Pan-Pan(宋攀攀)a), Zhang Zhi-Dong(张志东)b), and Guo Lian-Quan(郭连权)a)   

  1. a Shenyang University of Technology, Shenyang 110023, China; b  Shenyang National Laboratory for Materials Science, Institute of Metal Research and International Centre for Materials Physics, Chinese Academy of Sciences, Shenyang 110016, China
  • Received:2008-04-11 Revised:2008-05-12 Online:2008-10-20 Published:2008-10-20
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos 50331030, 10674139 and 10274087), and the Natural Science Foundation of Liaoning Province, China (Grant No 20062040).

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摘要： The magnon energy band in a four-layer ferromagnetic superlattice is studied by using the linear spin-wave approach and Green's function technique. It is found that three modulated energy gaps exist in the magnon energy band along $K_{x }$ direction perpendicular to the superlattice plane. The spin quantum numbers and the interlayer exchange couplings all affect the three energy gaps. The magnon energy gaps of the four-layer ferromagnetic superlattice are different from those of the three-layer one. For the four-layer ferromagnetic superlattice, the disappearance of the magnon energy gaps $\Delta \omega _{12} $, $\Delta \omega _{23} $ and $\Delta \omega _{34} $ all correlates with the symmetry of this system. The zero energy gap $\Delta \omega _{23}$ correlates with the symmetry of interlayer exchange couplings, while the vanishing of the magnon energy gaps $\Delta \omega _{12} $ and $\Delta \omega _{34} $ corresponds to a translational symmetry of $x$-direction in the lattice. When the parameters of the system deviate from these symmetries, the three energy gaps will increase.

关键词: layered ferromagnetic superlattice, magnon energy gap, spin quantum number, interlayer exchange couplings

Abstract: The magnon energy band in a four-layer ferromagnetic superlattice is studied by using the linear spin-wave approach and Green's function technique. It is found that three modulated energy gaps exist in the magnon energy band along $K_{x }$ direction perpendicular to the superlattice plane. The spin quantum numbers and the interlayer exchange couplings all affect the three energy gaps. The magnon energy gaps of the four-layer ferromagnetic superlattice are different from those of the three-layer one. For the four-layer ferromagnetic superlattice, the disappearance of the magnon energy gaps $\Delta \omega _{12} $, $\Delta \omega _{23} $ and $\Delta \omega _{34} $ all correlates with the symmetry of this system. The zero energy gap $\Delta \omega _{23}$ correlates with the symmetry of interlayer exchange couplings, while the vanishing of the magnon energy gaps $\Delta \omega _{12} $ and $\Delta \omega _{34} $ corresponds to a translational symmetry of $x$-direction in the lattice. When the parameters of the system deviate from these symmetries, the three energy gaps will increase.

Key words: layered ferromagnetic superlattice, magnon energy gap, spin quantum number, interlayer exchange couplings

中图分类号:  (Magnetic properties of interfaces (multilayers, superlattices, heterostructures))

  • 75.70.Cn
75.30.Ds (Spin waves) 75.30.Et (Exchange and superexchange interactions) 75.60.Ej (Magnetization curves, hysteresis, Barkhausen and related effects) 71.20.-b (Electron density of states and band structure of crystalline solids) 75.10.Jm (Quantized spin models, including quantum spin frustration)