First principle study on the effect of the photoelectric properties of (La, Ce)-doping Mn4Si7

Abstract

The effect of (La, Ce) doping on the electronic structure and optical properties of Mn4Si7 was studied by using the first-principles calculation method based on density functional theory. The results show that the lattice constant and cell volume of Mn4Si7 increase with rare earth doping, and the structure is more stable after doping. The most stable structure is Ce single doping system. Undoped Mn4Si7 is an indirect band gap semiconductor. Its band gap is 0.786 eV. La doping, Ce doping and La-Ce co-doping all decrease the band gap of Mn4Si7. The band gap is 0.229 eV, 0.247 eV and 0.072 eV, respectively. Undoped Mn4Si7 and La-doped Mn4Si7 are nonmagnetic, Ce-doped and La-Ce co-doped Mn4Si7 are diluted magnetic semiconductor. The static dielectric constant is increased by doping rare earth elements, and the maximum static dielectric constant is La-Ce co-doped system (61.73). The main peak of imaginary part of dielectric function moves to the low energy region in all doping systems and the value of the main peak of the doping system increases. The absorption spectra of the doped system show red shift, and a small new absorption peak appears at the photon energy of 8 eV. In the near infrared band, the absorption coefficient of Mn4Si7 is increased by rare earth doping. The absorption coefficient of La-Ce co-doping system is the largest (1.09 × 105 cm−1). Rare earth doping enhances the optical absorption performance of Mn4Si7.