Valley Hall Effect in Two-Dimensional Hexagonal Lattices

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

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Author(s)

Detail(s)

Original languageEnglish
Article number121006
Journal / PublicationJournal of the Physical Society of Japan
Volume84
Issue number12
Online published27 Nov 2015
Publication statusPublished - 15 Dec 2015
Externally publishedYes

Abstract

Valley is a quantum number defined for energetically degenerate but nonequivalent structures in energy bands of a crystalline material. Recent discoveries of two-dimensional (2D) layered materials have shed light on the potential use of this degree of freedom for information carriers because the valley can now be potentially manipulated in integrated 2D architectures. The valleys separated by a long distance in a momentum space are robust against external disturbance and the flow of the valley, the valley current, is nondissipative because it carries no net electronic current. Among the various 2D valley materials, graphene has by far the highest crystal quality, leading to an extremely long valley relaxation length in the bulk. In this review, we first describe the theoretical background of the valley Hall effect, which converts an electric field into a valley current. We then describe the first observation of the valley Hall effect in monolayer MoS2. Finally, we describe experiments on the generation and detection of the pure valley current in monolayer and bilayer graphene, achieved recently using the valley Hall effect and inverse valley Hall effect. While we show unambiguous evidence of a pure valley current flowing in graphene, we emphasize that the field of "valleytronics" is still in its infancy and that further theoretical and experimental investigations are necessary.

Citation Format(s)

Valley Hall Effect in Two-Dimensional Hexagonal Lattices. / Yamamoto, Michihisa; Shimazaki, Yuya; Borzenets, Ivan V. et al.
In: Journal of the Physical Society of Japan, Vol. 84, No. 12, 121006, 15.12.2015.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review