Intrinsic ferromagnetism and restrictive thermodynamic stability in MA${}_2$N${}_4$ and Janus VSiGeN${}_4$ monolayers

Abstract

The seminal experimental discovery of the remarkably stable MoSi${}_2$N${}_4$ monolayer has led to a handful of predicted magnetic two-dimensional (2D) materials in the MA${}_2$Z${}_4$ family (M = transition metals, A = Si, Ge, and Z = N, P, As). These magnetic monolayers were predicted to be dynamically stable, but none of them has been synthesized to date. In this Research Letter, from first-principles thermodynamic stability analysis, we demonstrate that only the nitrides are thermodynamically stable and this occurs under N-rich conditions. Based on this finding, we propose two ferromagnetic, semiconducting Janus monolayers in the family: VSiGeN${}_4$ and VSiSnN${}_4$. They are both dynamically and thermally stable, but only the former is thermodynamically stable. Intriguingly, Janus VSiGeN${}_4$ and VSiSnN${}_4$ monolayers show weak in-plane anisotropy compared with the VSi${}_2$N${}_4$ monolayer. These two emerging Janus magnetic semiconductors offer opportunities for studying 2D magnetism and spin control for spintronics applications.

Main article - 7 pages, 5 figures. Supplemental Material added

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Cited by in corpus (7)

• Strain effects on topological and valley properties of Janus monolayer $\mathrm{VSiGe}{\mathrm{N}}_4$
• A possible electronic state quasi-half-valley-metal in $\mathrm{VG}{\mathrm{e}}_2{\mathrm{P}}_4$ monolayer
• Manipulation of valley and spin properties in two-dimensional Janus WSiGeZ${}_4$ (Z=N,P, As) through symmetry control
• Correlation-driven topological transition in Janus VSiGeP2As2
• Importance of magnetic shape anisotropy in determining magnetic and electronic properties of monolayer $\mathrm{VS}{\mathrm{i}}_2{\mathrm{P}}_4$
• Manipulating Spin-Lattice Coupling in Layered Magnetic Topological Insulator Heterostructure $via$ Interface Engineering
• Tunable magnetic anisotropy, Curie temperature and band alignment of two-dimensional ferromagnet VSiSnN4 via non-volatile ferroelectrical control