Abstract
In this Letter, a tunable valley polarization is investigated for honeycomb systems with broken inversion symmetry such as transition-metal dichalcogenide MX2 (M = Mo, W; X = S, Se) monolayers through elliptical pumping. Compared to circular pumping, elliptical pumping is a more universal and effective method to create coherent valley polarization. When two valleys of MX2 monolayers are doped or polarized, a novel anomalous Hall effect (called valley orbital magnetic moment Hall effect) is predicted. Valley orbital magnetic moment Hall effect can generate an orbital magnetic moment current without the accompaniment of a charge current, which opens a new avenue for exploration of valleytronics and orbitronics. Valley orbital magnetic moment Hall effect is expected to overshadow spin Hall effect and is tunable under elliptical pumping.
Highlights
Valleytronics has generated great interest[1,2,3,4,5] in the field of condensed matter physics because it involves many novel phenomena such as valley Hall effect[6], valley-coupled spin Hall effect[7], and valley magnetic moment[8]
The valley-contrasting orbital magnetic moment in MX2 monolayers consists of two parts: one is from the parent atomic orbitals, and the other is from lattice structure
In this Letter, we have investigated the degree of polarization for two different valleys under elliptical pumping in MX2 monolayers
Summary
Zhigang Song[1], Ruge Quhe[1,4,5], Shunquan Liu[1], Yan Li1,2, Ji Feng[2,3], Yingchang Yang[1], Jing Lu1,2 & Jinbo Yang[1,2]. When two valleys of MX2 monolayers are doped or polarized, a novel anomalous Hall effect (called valley orbital magnetic moment Hall effect) is predicted. Valley orbital magnetic moment Hall effect can generate an orbital magnetic moment current without the accompaniment of a charge current, which opens a new avenue for exploration of valleytronics and orbitronics. Valley orbital magnetic moment Hall effect is expected to overshadow spin Hall effect and is tunable under elliptical pumping. The. Zeeman-type spin splittings in the VBM of MX2 monolayers are large enough (0.15–0.46 eV)[7,15] to observe valley-coupled spin Hall effect with hole carriers. The spin splittings in the CBM of MX2 monolayers are too small to observe the valley-coupled spin Hall effect with electron carriers. Valley orbital magnetic moment Hall effect is tunable by elliptical pumping. A new avenue is opened to the exploration of valleytronics and orbitronics
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