中国物理B ›› 2018, Vol. 27 ›› Issue (12): 127203-127203.doi: 10.1088/1674-1056/27/12/127203

• SPECIAL TOPIC—Recent advances in thermoelectric materials and devices • 上一篇    下一篇

Valley-polarized pumping current in zigzag graphene nanoribbons with different spatial symmetries

Zhizhou Yu(俞之舟), Fuming Xu(许富明)   

  1. 1 Center for Quantum Transport and Thermal Energy Science, School of Physics and Technology, Nanjing Normal University, Nanjing 210023, China;
    2 College of Physics and Energy, Shenzhen University, Shenzhen 518060, China
  • 收稿日期:2018-08-27 修回日期:2018-10-05 出版日期:2018-12-05 发布日期:2018-12-05
  • 通讯作者: Zhizhou Yu E-mail:yuzhizhou@njnu.edu.cn
  • 基金资助:

    Project supported by the National Natural Science Foundation of China (Grant Nos. 11704190, 11874221, and 11504240) and the Natural Science Foundation of Jiangsu Province, China (Grant No. BK20171030).

Valley-polarized pumping current in zigzag graphene nanoribbons with different spatial symmetries

Zhizhou Yu(俞之舟)1, Fuming Xu(许富明)2   

  1. 1 Center for Quantum Transport and Thermal Energy Science, School of Physics and Technology, Nanjing Normal University, Nanjing 210023, China;
    2 College of Physics and Energy, Shenzhen University, Shenzhen 518060, China
  • Received:2018-08-27 Revised:2018-10-05 Online:2018-12-05 Published:2018-12-05
  • Contact: Zhizhou Yu E-mail:yuzhizhou@njnu.edu.cn
  • Supported by:

    Project supported by the National Natural Science Foundation of China (Grant Nos. 11704190, 11874221, and 11504240) and the Natural Science Foundation of Jiangsu Province, China (Grant No. BK20171030).

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摘要：

We numerically investigate the valley-polarized current in symmetric and asymmetric zigzag graphene nanoribbons (ZGNRs) by the adiabatic pump, and the effect of spatial symmetry is considered by introducing different pumping regions. It is found that pumping potentials with the symmetry Vp(x,y)=Vp(-x,y) can generate the largest valley-polarized current. The valley-polarized currents I13L with the pumping potential symmetry Vp(x,y)=Vp(x,-y) and I14L with Vp(x,y)=Vp(-x,-y) of symmetric ZGNRs are much smaller than those of asymmetric ZGNRs. We also find I13L and I14L of symmetric ZGNRs decrease and increase with the increasing pumping amplitude, respectively. Moreover, the dephasing effect from the electron-phonon coupling within the Buttiker dephasing scheme is introduced. The valley-polarized current of the symmetric ZGNRs with Vp(x,y)=Vp(x,-y) increases with the increase of the dephasing strength while that with Vp(x,y)=Vp(-x,-y) decreases as the dephasing strength increases.

关键词: valley polarization, charge pump, graphene, quantum transport

Abstract:

We numerically investigate the valley-polarized current in symmetric and asymmetric zigzag graphene nanoribbons (ZGNRs) by the adiabatic pump, and the effect of spatial symmetry is considered by introducing different pumping regions. It is found that pumping potentials with the symmetry Vp(x,y)=Vp(-x,y) can generate the largest valley-polarized current. The valley-polarized currents I13L with the pumping potential symmetry Vp(x,y)=Vp(x,-y) and I14L with Vp(x,y)=Vp(-x,-y) of symmetric ZGNRs are much smaller than those of asymmetric ZGNRs. We also find I13L and I14L of symmetric ZGNRs decrease and increase with the increasing pumping amplitude, respectively. Moreover, the dephasing effect from the electron-phonon coupling within the Buttiker dephasing scheme is introduced. The valley-polarized current of the symmetric ZGNRs with Vp(x,y)=Vp(x,-y) increases with the increase of the dephasing strength while that with Vp(x,y)=Vp(-x,-y) decreases as the dephasing strength increases.

Key words: valley polarization, charge pump, graphene, quantum transport

中图分类号:  (Electronic transport in graphene)

  • 72.80.Vp
73.63.-b (Electronic transport in nanoscale materials and structures) 73.23.-b (Electronic transport in mesoscopic systems) 85.75.-d (Magnetoelectronics; spintronics: devices exploiting spin polarized transport or integrated magnetic fields)