中国物理B ›› 2020, Vol. 29 ›› Issue (7): 77304-077304.doi: 10.1088/1674-1056/ab8db2

• SPECIAL TOPIC—Ultracold atom and its application in precision measurement • 上一篇    下一篇

Improvement of valley splitting and valley injection efficiency for graphene/ferromagnet heterostructure

Longxiang Xu(徐龙翔), Wengang Lu(吕文刚), Chen Hu(胡晨), Qixun Guo(郭奇勋), Shuai Shang(尚帅), Xiulan Xu(徐秀兰), Guanghua Yu(于广华), Yu Yan(岩雨), Lihua Wang(王立华), Jiao Teng(滕蛟)   

  1. 1 Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing, 100083, China;
    2 Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;
    3 Beijing Key Laboratory for Nanomaterials and Nanodevices, Beijing 100190, China;
    4 Center for the Physics of Materials and Department of Physics, McGill University, Montreal, Quebec H3A 2T8, Canada;
    5 Corrosion and Protection Center, Key Laboratory for Environmental Fracture(MOE), University of Science and Technology Beijing, Beijing 100083, China;
    6 Institute of Microstructure and Property of Advanced Materials, Beijing Key Laboratory of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124, China
  • 收稿日期:2020-04-11 修回日期:2020-04-22 出版日期:2020-07-05 发布日期:2020-07-05
  • 通讯作者: Wengang Lu, Jiao Teng E-mail:wglu@iphy.ac.cn;tengjiao@mater.ustb.edu.cn
  • 基金资助:
    Project supported by the National Key R&D Program of China (Grant No. 2017YFF0206104), the National Natural Science Foundation of China (Grant No. 51871018), Beijing Laboratory of Metallic Materials and Processing for Modern Transportation, the Opening Project of Key Laboratory of Microelectronics Devices & Integrated Technology, Institute of Microelectronics of Chinese Academy of Sciences, Beijing Natural Science Foundation, China (Grant No. Z180014), and Beijing Outstanding Young Scientists Projects, China (Grant No. BJJWZYJH01201910005018). We gratefully acknowledge the Chinese Academy of Sciences for providing computation facilities.

Improvement of valley splitting and valley injection efficiency for graphene/ferromagnet heterostructure

Longxiang Xu(徐龙翔)1, Wengang Lu(吕文刚)2,3, Chen Hu(胡晨)4, Qixun Guo(郭奇勋)1, Shuai Shang(尚帅)1, Xiulan Xu(徐秀兰)1, Guanghua Yu(于广华)1, Yu Yan(岩雨)5, Lihua Wang(王立华)6, Jiao Teng(滕蛟)1   

  1. 1 Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing, 100083, China;
    2 Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;
    3 Beijing Key Laboratory for Nanomaterials and Nanodevices, Beijing 100190, China;
    4 Center for the Physics of Materials and Department of Physics, McGill University, Montreal, Quebec H3A 2T8, Canada;
    5 Corrosion and Protection Center, Key Laboratory for Environmental Fracture(MOE), University of Science and Technology Beijing, Beijing 100083, China;
    6 Institute of Microstructure and Property of Advanced Materials, Beijing Key Laboratory of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124, China
  • Received:2020-04-11 Revised:2020-04-22 Online:2020-07-05 Published:2020-07-05
  • Contact: Wengang Lu, Jiao Teng E-mail:wglu@iphy.ac.cn;tengjiao@mater.ustb.edu.cn
  • Supported by:
    Project supported by the National Key R&D Program of China (Grant No. 2017YFF0206104), the National Natural Science Foundation of China (Grant No. 51871018), Beijing Laboratory of Metallic Materials and Processing for Modern Transportation, the Opening Project of Key Laboratory of Microelectronics Devices & Integrated Technology, Institute of Microelectronics of Chinese Academy of Sciences, Beijing Natural Science Foundation, China (Grant No. Z180014), and Beijing Outstanding Young Scientists Projects, China (Grant No. BJJWZYJH01201910005018). We gratefully acknowledge the Chinese Academy of Sciences for providing computation facilities.

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摘要： The valley splitting has been realized in the graphene/Ni heterostructure with the splitting value of 14 meV, and the obtained valley injecting efficiency from the heterostructure into graphene was 6.18% [Phys. Rev. B 92 115404 (2015)]. In this paper, we report a way to improve the valley splitting and the valley injecting efficiency of the graphene/Ni heterostructure. By intercalating an Au monolayer between the graphene and the Ni, the split can be increased up to 50 meV. However, the valley injecting efficiency is not improved because the splitted valley area of graphene moves away from the Fermi level. Then, we mend the deviation by covering a monolayer of Cu on the graphene. As a result, the valley injecting efficiency of the Cu/graphene/Au/Ni heterostructure reaches 10%, which is more than 60% improvement compared to the simple graphene/Ni heterostructure. Then we theoretically design a valley-injection device based on the Cu/graphene/Au/Ni heterostructure and demonstrate that the valley injection can be easily switched solely by changing the magnetization direction of Ni, which can be used to generate and control the valley-polarized current.

关键词: valleytronics, two-dimensional materials, valley-polarized transport

Abstract: The valley splitting has been realized in the graphene/Ni heterostructure with the splitting value of 14 meV, and the obtained valley injecting efficiency from the heterostructure into graphene was 6.18% [Phys. Rev. B 92 115404 (2015)]. In this paper, we report a way to improve the valley splitting and the valley injecting efficiency of the graphene/Ni heterostructure. By intercalating an Au monolayer between the graphene and the Ni, the split can be increased up to 50 meV. However, the valley injecting efficiency is not improved because the splitted valley area of graphene moves away from the Fermi level. Then, we mend the deviation by covering a monolayer of Cu on the graphene. As a result, the valley injecting efficiency of the Cu/graphene/Au/Ni heterostructure reaches 10%, which is more than 60% improvement compared to the simple graphene/Ni heterostructure. Then we theoretically design a valley-injection device based on the Cu/graphene/Au/Ni heterostructure and demonstrate that the valley injection can be easily switched solely by changing the magnetization direction of Ni, which can be used to generate and control the valley-polarized current.

Key words: valleytronics, two-dimensional materials, valley-polarized transport

中图分类号:  (Electronic transport in nanoscale materials and structures)

  • 73.63.-b
72.80.Vp (Electronic transport in graphene) 85.75.-d (Magnetoelectronics; spintronics: devices exploiting spin polarized transport or integrated magnetic fields)