Two-Dimensional Iron Silicide (FeSi<sub><i>x</i></sub>) Alloys with Above-Room-Temperature Ferromagnetism.

Niu, Yijie; Zhang, Kai; Cui, Xuefeng; Wu, Xiaojun; Yang, Jinlong · Nano Lett · 2023

basic_science · Level V

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Abstract

Two-dimensional (2D) materials with intrinsic room-temperature ferromagnetism have gathered tremendous interest as promising candidates for next-generation spintronics. Here, on the basis of first-principles calculations, we report a family of stable 2D iron silicide (FeSi<sub><i>x</i></sub>) alloys via dimensional reduction of their bulk counterparts. Our results demonstrate that 2D Fe<sub>4</sub>Si<sub>2</sub>-hex, Fe<sub>4</sub>Si<sub>2</sub>-orth, Fe<sub>3</sub>Si<sub>2</sub>, and FeSi<sub>2</sub> nanosheets are lattice-dynamically and thermally stable, confirmed by the calculated phonon spectra and Born-Oppenheimer dynamic simulation up to 1000 K. 2D FeSi<sub><i>x</i></sub> nanosheets are ferromagnetic metals with estimated Curie temperatures ranging from 547 to 971 K due to strong direct exchange interaction between Fe sites. In addition, the electronic properties of 2D FeSi<sub><i>x</i></sub> alloys can be maintained on silicon substrates, providing an ideal platform for spintronics applications in the nanoscale.