Predicted septuple-atomic-layer Janus MSiGeN₄ (M = Mo and W) monolayers with Rashba spin splitting and high electron carrier mobilities

Abstract

In this work, Janus monolayers are predicted for a new 2D MA2Z4 family by means of first-principles calculations. The predicted MSiGeN4 (M = Mo and W) monolayers exhibit dynamic, thermodynamic and mechanical stability, and they are indirect band-gap semiconductors.

Novel Janus GaInX3 (X = S, Se, Te) single-layers: first-principles prediction on structural, electronic, and transport properties

“…The values of the C 2D and E d are obtained by tting the strain-dependent energy and band-edge position. 32,33 The strain-dependent energy change and band edge positions of all three Janus structures GaInX 3 are shown in Fig. 7.…”

Piezoelectric quantum spin Hall insulator with Rashba spin splitting in Janus monolayer $\mathrm{SrAlGaSe_4}$

“…The calculated C 2D is 71.68 Nm −1 , which are very smaller than ones of monolayer MSi 2 N 4 (M=Ti, Zr, Hf, Cr, Mo and W) and Janus MSiGeN 4 (M=Mo and W) 15,49 , indicating that monolayer SrAlGaSe 4 is not rigid. The Poisson's ratio ν is also calculated by C 12 /C 11 , and it is 0.37.…”

“…Firstly, the C 11 and C 12 are calculated with GGA by SSR, and they are 54.14 Nm −1 and 23.30 Nm −1 , which are smaller than ones of unstrained SrAlGaSe 4 monolayer. Tensile strain reduced C 11 and C 12 have been found in many 2D materials 49,55 . And then, we use the orthorhombic supercell as the computational cell (in…”

“…As plotted in Figure 1, there is no imaginary vibrational frequency with three acoustic and eighteen optical phonon branches, which clearly suggests that SrAlGaSe 4 monolayer is dynamically stable. Moreover, both linear and flexural modes occur around the Γ point, which can be observed in most 2D materials 34,49,50 . In addition, by performing ab-initio molecular dynamics (AIMD) simulations, we examine the thermal stability of SrAlGaSe 4 monolayer with a supercell of 4×4×1 for more than 3000 fs at 300 K. The temperature and total energy fluctuations of SrAlGaSe 4 monolayer as a function of simulation time are plotted in Figure 2, along with the crystal structures of SrAlGaSe 4 at 300 K after the simulation for 3 ps.…”

Substitutional transition metal doping in MoSi2N4 monolayer: structural, electronic and magnetic properties

“…29 This made MoSiN the focus of intensive research aiming to uncover its novel properties. [30][31][32][33][34][35][36][37][38][39] Following the successful MoSiN preparation, many MX 2 Y 4 (M = Cr, V, Mo, W, Ta; X = Si, Ge; and Y = N, As, P) monolayers have been studied. 40,41 It was found that WSi 2 N 4 , CrSi 2 N 4 , and MoSi 2 N 4 monolayers have the highest piezoelectric coefficients as compared with the other known 2D materials.…”