Realization of Valley and Spin Pumps by Scattering at Nonmagnetic Disorders

Xing Tao An, Jiang Xiao, M. W.Y. Tu, Hongyi Yu, Vladimir I. Fal'Ko, Wang Yao

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

The recent success in optical pumping of valley polarization in two-dimensional transition metal dichalcogenides (TMDs) has greatly promoted the concept of valley-based informatics and electronics. However, between the demonstrated valley polarization of transient electron-hole pair excitations and practical valleytronic operations, there exist obvious gaps to fill, among which is the valley pump of long-lived charge carriers. Here we discover that the quested valley pump of electrons or holes can be realized simply by scattering at the ubiquitous nonmagnetic disorders, not relying on any specific material property. The mechanism is rooted in the nature of the valley as a momentum space index: the intervalley backscattering in general has a valley contrasted rate due to the distinct momentum transfers, causing a net transfer of population from one valley to another. As examples, we numerically demonstrate the sizable valley pump effects driven by charge current in nanoribbons of monolayer TMDs, where the spin-orbit scattering by nonmagnetic disorders also realizes a spin pump for the spin-valley locked holes. Our finding points to a new opportunity towards valley spintronics, turning disorders from a deleterious factor to a resource of valley and spin polarization.

Original languageAmerican English
Article number096602
JournalPhysical Review Letters
Volume118
Issue number9
DOIs
StatePublished - 1 Mar 2017
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2017 American Physical Society.

Fingerprint

Dive into the research topics of 'Realization of Valley and Spin Pumps by Scattering at Nonmagnetic Disorders'. Together they form a unique fingerprint.

Cite this