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The magnetic properties of M2AX (M = Mn, Fe; A = Al, Ga, Si, Ge; X = C, N) phases were studied within DFT-GGA. The magnetic electronic ground state is determined. The investigation of the phase stability of M2AX phases is performed by comparing the total energy of MAX phases to that of the set of competitive phases for calculation of the phase formation enthalpy. As the result of such an approach, we have found one stable compound (Mn2GaC), and seven metastable ones. It is shown that several metastable MAX phases (Mn2AlC, Fe2GaC, Mn2GeC, and Mn2GeN) become stable at a small applied pressure (1.5–7 GPa). The mechanical, electronic and elastic properties of metastable MAX phases are studied. [ABSTRACT FROM AUTHOR]

The effect of the local environment on the formation of magnetic moments on Mn atoms in manganese silicide Mn3Si is studied by the combination of ab initio calculations and the model analysis. The suggested approach is related to the self‐consistent mapping of the results of ab initio calculations to a multiorbital model. The model analysis allows to reveal the role played by the local environment of the transition metal atoms on the magnetic moments formation. It is found that the formation of the magnetic moment is controlled rather by hopping parameters between Mn atoms, not by the number of Mn–Si nearest neighbors. Particularly, the formation of magnetic moment on MnI atom is mainly controlled by the hopping parameter between nearest Mn atoms, while the magnetic moment on MnII atom is primarily determined by the hoppings between next‐nearest Mn atoms. The obtained phase diagrams of the magnetic state show the presence of a sharp boundary with respect to the hopping between Mn atoms. This opens the opportunity to turn on or turn off the magnetic state by the external impacts. The ab initio calculations of Mn3Si well agree with the results of model consideration and confirm the model conclusions. [ABSTRACT FROM AUTHOR]

Since their discovery in 2011, the MXene family of two-dimensional (2D) materials has attracted much interest due to its unique properties, leading to practical applications. Recently, special attention has been paid to magnetic MXenes. However, despite the great diversity of the chemical composition of MXenes, which opens up prospects for obtaining magnetic 2D materials, only a few MXenes with intrinsic magnetism have been synthesized to date. The main reason for this is the phase instability of both MXenes and their parent MAX phases. Here, we use the first-principles calculations and the cluster expansion (CE) method to analyze the thermodynamic stability of second-order MXenes (M1 1- x M2 x ) 3 C 2 and their parent MAX phases with two transition metals (M1 = V, Cr; M2 = Mn, Cr). Our analysis allows us to identify the most stable MXene structures with possible magnetism. In the stable structures found, the electronic and magnetic properties were calculated. The effect of surface functionalization with fluorine and oxygen on the properties of the MXenes was also studied. It was found that the most promising for synthesis is (V 1/3 Mn 2/3 ) 3 C 2 , which is ferromagnetic with a large magnetic moment per cell, both in bare form and with functionalization of its surface with fluorine.

The magnetic properties of M 2 AX (M = Mn, Fe; A = Al, Ga, Si, Ge; X = C, N) phases were studied within DFT-GGA. The magnetic electronic ground state is determined. The investigation of the phase stability of M 2 AX phases is performed by comparing the total energy of MAX phases to that of the set of competitive phases for calculation of the phase formation enthalpy. As the result of such an approach, we have found one stable compound (Mn 2 GaC), and seven metastable ones. It is shown that several metastable MAX phases (Mn 2 AlC, Fe 2 GaC, Mn 2 GeC, and Mn 2 GeN) become stable at a small applied pressure (1.5-7 GPa). The mechanical, electronic and elastic properties of metastable MAX phases are studied.