Electrical valley filtering in transition metal dichalcogenides

Abstract

This work investigates the feasibility of electrical valley filtering for holes in transition metal dichalcogenides. We look specifically into the scheme that utilizes a potential barrier to produce valleydependent tunneling rates, and perform the study with both a kp  based analytic method and a recursive Green's function based numerical method. The study yields the transmission coefficient as a function of incident energy and transverse wave vector, for holes going through lateral quantum barriers oriented in either armchair or zigzag directions, in both homogeneous and heterogeneous systems. The main findings are the following: 1) the tunneling current valley polarization increases with increasing barrier width or height, 2) both the valley-orbit interaction and band structure warping contribute to valley-dependent tunneling, with the former contribution being manifest in structures with asymmetric potential barriers, and the latter being orientation-dependent and reaching maximum for transmission in the armchair direction, and 3) for transmission ~ 0.1, a tunneling current valley polarization of the order of 10% can be achieved.

Topological kink states in graphene

“…Valley filters [66,[94][95][96][97][98][99][100][101][102][103][104], serving as valley polarized current generators and allowing only carriers of a specific valley passing through, are one important type of valleytronics devices. Figures 12(a) and (b) depict monolayer and bilayer graphene based two-terminal valley filters, respectively.…”

Tunable valley filter efficiency by spin–orbit coupling in silicene nanoconstrictions*

“…Valley filters are realized in quantum point contact, [6,7] and other structures with nanobubble, [8,9] domain wall, [10,11] Corbino nanodisk [12,13] or Weyl semimetals. [14,15] In addition, mechanical, [16][17][18] optical, [19][20][21] magnetic [22][23][24] and electrical [25][26][27] methods have been applied to process valley information.…”

Valley polarized current and resonant electronic transport in a nonuniform MoS2 zigzag nanoribbon

“…While the valley polarization of the charge carriers was extensively studied for bulk monolayers much less attention was paid to its implications on the electronic transport in nanostructures. It has been shown that the valley polarization can be induced in graphene nanoribbons 29 or for hole charge carriers in TMDCs nanostructures 30 by tailoring the shape and potential profile of the structure.…”