Protected valley states and generation of valley- and spin-polarized current in monolayer MA2Z4

Abstract

The optical selection rules obeyed by two-dimensional materials with spin-valley coupling enable the selective excitation of carriers. We show that six members of the monolayer MA2Z4 (M = Mo and W; A = C, Si, and Ge; Z = N, P, and As) family are direct band-gap semiconductors with protected valley states and that circularly polarized infrared light can induce valley-selective inter-band transitions. Our optovalleytronic device demonstrates a close to 100% valley- and spin-polarized current under in-plane bias and circularly polarized infrared light, which can be exploited to encode, process, and store information.

6 figures

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Cited by in corpus (3)

• MoSi${}_2$N${}_4$-like crystals -- the new family of two-dimensional materials
• Fast electrically switchable large gap quantum spin Hall states in MGe${}_2$Z${}_4$
• Interlayer couplings in homobilayer structures of MSi2X4 (M = Mo/W, X = N/P/As)