Predicted ferromagnetic monolayer CrSCl with large vertical piezoelectric response: A first-principles study

Abstract

For two-dimensional (2D) materials, piezoelectric ferromagnetism with large out-of-plane piezoresponse is highly desirable for multifunctional ultrathin piezoelectric device application. Here, we predict that Janus monolayer CrSCl is an out-of-plane ferromagnetic semiconductor with large vertical piezoelectric response and high Curie temperature. The predicted out-of-plane piezoelectric strain coefficient d31 is −1.58 pm/V, which is higher than that of most 2D materials (compare absolute values of d31). The large out-of-plane piezoelectricity is robust against electronic correlation and biaxial strain, confirming reliability of large d31. The calculated results show that tensile strain is conducive to high Curie temperature, large magnetic anisotropy energy, and large d31. Finally, by comparing d31 of CrYX (Y = S; X = Cl, Br, I) and CrYX (Y = O; X = F, Cl, Br), we conclude that the size of d31 is positively related to electronegativity difference of X and Y atoms. Such findings can provide valuable guidelines for designing 2D piezoelectric materials with large vertical piezoelectric response.

Combined piezoelectricity, valley splitting and Dzyaloshinskii–Moriya interaction in Janus GdXY (X, Y = Cl, Br, I) magnetic semiconductors

“…The calculated IP piezoelectric constants e 11 and d 11 of GdXY are about 80 pC m −1 and 2.8 pm V −1 , respectively, which are smaller but still comparable to those of conventional transition metal dichalcogenides, 49–51 since halogens gain fewer electrons than chalcogens. In particular, due to Cl and I atoms having the largest electronegativity difference, as discussed in other work, 52,53 GdClI has the largest OOP piezoelectric constants e 31 and d 31 , which are 82 pC m −1 and 1.5 pm V −1 , respectively. The OOP piezoelectric constants of monolayer GdXY are larger than most previously discovered 2D Janus materials.…”

Two-dimensional Janus Si dichalcogenides: a first-principles study

“…We note that this value of d 11 is larger than most reported 2D materials, 8 perhaps only lower than some members of the SnSe family (such as 2D SnSe and GeSe). The magnitude of d 31 is also large among the existing 2D materials (although some predicted structures may achieve even higher values 46,47 ). In Fig.…”

Direct tuning of large-gap quantum spin Hall effect in mono transition metal carbide MXenes

“…The calculated acoustic branches display a clear linear mode along the G-M direction, which shows the general characteristics of 2D materials. [59][60][61][62] The phonon density of states shows that the lowest acoustic branch consists of the Ta atoms. Additionally, all the acoustic branch frequencies are positive and there are no imaginary frequencies in the phonon spectra of the Ta 2 CF 2 monolayer, which indicates that the structure has dynamical stability.…”