Control of spin diffusion and suppression of the Hanle oscillation by the coexistence of spin and valley Hall effects in Dirac materials

Xian Peng Zhang, Chunli Huang, Miguel A. Cazalilla

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In addition to spin, electrons in many Dirac materials possess an additional pseudospin degree of freedom known as "valley." In materials where the spin and valley degrees of freedom are weakly coupled, they can be both excited and controlled independently. In this work, we study a model describing the interplay of the spin and valley Hall effects in such two-dimensional materials. We demonstrate the emergence of an additional longitudinal neutral current that is both spin and valley polarized. The additional neutral current allows to control the spin density by tuning the magnitude of the valley Hall effect. In addition, the interplay of the two effects can suppress the Hanle oscillation, that is, the oscillation of the nonlocal resistance of a Hall bar device with in-plane magnetic field. The latter observation provides a possible explanation for the absence of the Hanle oscillation in a number of recent experiments. Our work also opens the possibility to engineer the conversion between the valley and spin degrees of freedom in two-dimensional materials.

Original languageEnglish
Article number245106
JournalPhysical Review B
Issue number24
StatePublished - Jun 5 2019

Bibliographical note

Funding Information:
This work is supported by the Ministry of Science and Technology (Taiwan) under Contracts No. 102-2112-M-007-024-MY5 and No. CL 107-2112-M-007-021-MY5 (M.A.C. and C.H.), the Spanish Ministerio de Economía y Competitividad (MINECO) under Projects No. FIS2014-55987-P and No. FIS2017-82804-P (X.-P.Z. and C.H.), and Taiwan's National Center of Theoretical Sciences (M.A.C. and C.H.). C.H. was supported in part by DOE Basic Energy Sciences under Award No. DE-FG02-02ER45958 and also acknowledges funding by Ministry of Science and Technology (Taiwan) through Project No. 107-2917-I-564-009. We thank F. Guinea, A. Kaverzin, and R. Stephen for useful discussions.

Publisher Copyright:
© 2019 American Physical Society.

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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