Janus XGeN3 (X = Cr, Mn, Fe) monolayer with large out-of-plane magnetic anisotropy and high Curie temperature

Two-dimensional magnetic materials have garnered extensive attention for their exceptional properties and diverse applications, yet their low Curie temperature (Tc) and in-plane magnetic anisotropy severely hinder practical deployment. Herein, via first-principles calculations, we predict Janus XGeN3 (X = Cr, Mn, Fe) monolayers as promising candidates for next-generation spintronics. We systematically verify their stabilities from dynamic, mechanical, and thermodynamic perspectives. Notably, CrGeN3 and FeGeN3 exhibit robust ferromagnetic coupling with Tc of 304 and 317 K, while MnGeN3 shows antiferromagnetic behavior. All three monolayers possess the large out-of-plane magnetic anisotropy energies as 19.16 μeV/Cr, 46.13 μeV/Mn, and 70.16 μeV/Fe. Furthermore, MnGeN3 and FeGeN3 have band gaps of 0.18 and 0.14 eV, respectively, while CrGeN3 exhibits half-metallic properties. These theoretical predictions of Janus XGeN3 monolayers with high Tc and out-of-plane magnetic anisotropy highlight their great potential for spintronic devices and nanoscale sensors.