EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Two-dimensional (2D) crystals have been attracting enormous research interest owing to their great potential in the future nanoelectronics. In particular, 2D magnetic materials have gained more and more attention recently. Nevertheless, most of the 2D materials are intrinsically non-magnetic, and strategies like impurity doping, defect engineering, etc. are investigated extensively to induce magnetism in 2D materials. In this work, we systematically explore and investigate the possible 2D structures of aluminum nitrides by the combination of the Universal Structure Predictor: Evolutionary Xtallography (USPEX) method and Density functional theory calculation. We find that the stoichiometry of 1:1 has the lowest global energy for the 2D aluminum nitrides. Their stability is also confirmed by phonon calculations. Meanwhile, the non-magnetic 2D aluminum nitrides can become ferromagnetic under hole doping over a wide range of hole concentrations, which could be the result of their large density of states in the vicinity of the valence band top that fulfills the Stoner criteria. Generally, the spin polarization energy (defined as the total energy difference between the non-magnetic state and the ferromagnetic state) increases monotonously with the increase of the hole density, and the injected holes can be fully spin-polarized. By means of Monte Carlo simulations, the Curie temperatures (Tc) under different hole doping densities are predicted, and the maximum Tc of about 100 K to 200 K are observed for the 2D aluminum nitrides.