A tetragonal phase Mn2B2 sheet: a stable room temperature ferromagnet with sizable magnetic anisotropy.

Exploring the magnetic properties of two-dimensional (2D) metal boride (MBene) sheets for spin-based electronics is gaining importance for developing electronic devices. Through combined first-principles calculations and Monte Carlo simulations, we present a new tetragonal Mn2B2 (tetra-Mn2B2) sheet. The tetra-Mn2B2 sheet shows metallic ferromagnetism (2.65 µB per Mn atom) with excellent stability. Moreover, it is demonstrated that the tetra-Mn2B2 sheet holds promise for experimental synthesis within an acceptable range from the results of stability tests of tetra-Mn2B2. We also find that the magnetic anisotropy (MAE) of the 2D tetra-Mn2B2 sheet is significantly increased under an electric field. The Curie temperature (TC) of the tetra-Mn2B2 sheet is calculated as 406 K. This 2D tetra-Mn2B2 with a high Curie temperature can serve as a promising candidate for future magnetoelectronics applications.

First-principles studies on the effects of halogen adsorption on monolayer antimony.

Using first-principles calculations, we carry out systematic studies on the electronic, magnetic and structural properties of halogenated ß-phase antimonene. We consider two different levels of halogen adatom coverage i.e. Θ = 1/8 and Θ = 1/18. It is found that F, Cl and Br adatoms act as acceptors whereas the I adatom acts as a donor. For a high coverage of Θ = 1/8, halogenated ß-phase antimonene exhibits metallic characteristics. With a lower coverage of Θ = 1/18, through the adsorption of F, Cl and Br the semiconducting unstrained antimonene becomes metallic. In contrast, I-adsorbed antimonene remains semiconducting but exhibits magnetic behavior. We further investigate the effects of bi-axial strain on the halogenated ß-phase antimonene. It is found that bi-axial strain can only induce ferromagnetism on the halogenated antimonene at Θ = 1/18. However, the ferromagnetism is suppressed when the applied strain is high. We uncover that the emergence of strain-dependent magnetism is attributed to the presence of localized states in the bandgap resulting from collective effects of bi-axial strain and the adsorption of halogen atoms.