Giant Carrier Mobility in a Room-Temperature Ferromagnetic VSi<sub>2</sub>N<sub>4</sub> Monolayer.

Qiao, Lei; Li, Musen; Cui, Yaning; Xu, Shaowen; Reimers, Jeffrey R; Ren, Wei · Nano Lett · 2024

basic_science · Level V

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Abstract

Using density functional theory (DFT), we investigate that two possible phases of VSi<sub>2</sub>N<sub>4</sub> (VSN) may be realized, one called the "H phase" corresponding to what is known from calculation and herein the other new "T phase" being stabilized by a biaxial tensile strain of 3%. Significantly, the H phase is predicted to display a giant carrier mobility of 1 × 10<sup>6</sup> cm<sup>2</sup> V<sup>-1</sup> s<sup>-1</sup>, which exceeds that for most 2D magnetic materials, with a Curie temperature (<i>T</i><sub>C</sub>) exceeding room temperature and a band gap of 2.01 eV at the K point. Following the H-T phase transition, the direct band gap shifts to the Γ point and increases to 2.59 eV. The Monte Carlo (MC) simulations also indicate that <i>T</i><sub>C</sub> of the T phase VSN can be effectively modulated by strain, reaching room temperature under a biaxial strain of -4%. These results show that VSN should be a promising functional material for future nanoelectronics.