First-principles study on electronic structure, magnetic and dielectric properties of Cr-doped Fe₃C

Abstract

The first-principles calculations were performed to investigate the electronic structure, magnetic and dielectric properties of Cr-doped Fe₃C, in comparison to those of pure Fe₃C and Cr₃C. The obtained results show that the thermodynamic stability of Cr-doped Fe₃C becomes weaker in terms of the larger formation enthalpy, on the contrary, the metallicity and covalency are found to strengthen to some extent. The magnetic moments of Fe₃C, Fe₁₁CrC₄(g), and Fe₁₁CrC₄(s) are respectively 21.36 μ_B/cell, 16.92 μ_B/cell, and 17.62 μ_B/cell, and in Fe₁₁CrC₄(g) and Fe₁₁CrC₄(s), the Fe of Wyckoff positions of 8d and 4c is substituted by Cr. The local magnetic moment of Cr at 8d site is larger than that at 4c site in the doped structure, which is opposite to that of Fe. In low frequency band, the permittivity follows the ranking of Fe₁₁CrC₄(s)>Cr₃C>Fe₁₁CrC₄(g)>Fe₃C. Once exceeding a certain frequency, the sequence will be broken. Besides the electron transition, the polarization of atoms also makes a contribution to the dielectric properties.

Keywords

Cr-doped Fe₃C / electronic structure / magnetic properties / dielectric properties

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