Giant Seebeck magnetoresistance triggered by electric field and assisted by a valley through a ferromagnetic/antiferromagnetic junction in heavy group-IV monolayers

Xuechao Zhai, Junwei Gu, Rui Wen, Ruo-Wen Liu, Min Zhu, Xingfei Zhou, L.-Y. Gong, and Xing'ao Li
Phys. Rev. B 99, 085421 – Published 19 February 2019

Abstract

Electrons in heavy group-IV monolayers, including silicene, germanene, and stanene, have the ability to exhibit rich physics due to the compatibility of the spin and valley degrees of freedom. We propose here that a valley-mediated giant Seebeck magnetoresistance (MR) effect, triggered and controlled by an interlayer electric field Ez, can be engineered near room temperature in a ferromagnetic/antiferromagnetic (FM/AFM) junction based on heavy group-IV monolayers, where the FM and AFM fields can be induced by the proximity effect, and Ez is locally applied in the AFM region. Attributed to the specific tunneling mechanism of spin-valley matching, the high thermal MR state is dominated by a Seebeck state with nearly pure spin current (no charge current) from one valley under Ez=0, while the low thermal MR state is dominated by a spin filter state from the other valley under Ez0. We also demonstrate that such a giant Seebeck MR effect is robust against the small perturbation of the Fermi level, and is sensitive to Ez by changing the electron-hole transport symmetry and tuning the bands. Further calculations indicate that the Seebeck MR effect is relatively too weak in other magnetic junctions, typically the FM/Ez and AFM/Ez junctions, even when the pure-spin-current state is present. These findings may pave the way for heavy group-IV monolayers in developing valley-assisted thermomagnetic storing and reading technologies in future spin caloritronic devices.

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  • Received 5 September 2018
  • Revised 4 January 2019

DOI:https://doi.org/10.1103/PhysRevB.99.085421

©2019 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Xuechao Zhai1,*, Junwei Gu1, Rui Wen2, Ruo-Wen Liu2, Min Zhu1, Xingfei Zhou1, L.-Y. Gong1,†, and Xing'ao Li1,‡

  • 1New Energy Technology Engineering Laboratory of Jiangsu Province & School of Science, Nanjing University of Posts and Telecommunications (NJUPT), Nanjing 210023, China
  • 2College of Electronic and Optical Engineering, and College of Microelectronics, Nanjing University of Posts and Telecommunications, Nanjing 210023, China

  • *zxc@njupt.edu.cn
  • lygong@njupt.edu.cn
  • lixa@njupt.edu.cn

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Issue

Vol. 99, Iss. 8 — 15 February 2019

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