Effect of carbon doping on electronic transitions in Mn5Ge3

Abstract

Mn5Ge3 is a ferromagnetic compound with high Curie temperature (Tc = 293 K), high spin polarization, and a good lattice match to germanium. Doping Mn5Ge3 with carbon increases Tc above room temperature and makes these compounds promising candidates for spin injectors for potential spintronics applications. The resistivity and magnetic susceptibility measurements show anisotropic behavior of these compounds. Optical spectroscopy is employed to measure near-normal reflectance of Mn5Ge3C0.89 in the frequency range from far-infrared to ultraviolet at three different temperatures (10, 200, and 300 K), and results are compared with those on pure Mn5Ge3. Both Mn5Ge3 and Mn5Ge3C0.89 have weak temperature dependence of the optical properties in the 10–300 K range, and both have similar electrodynamics responses with similar temperature trends. However, important differences in the region of interband transitions, indicating the electronic nature of the increased ferromagnetic stability of carbon doped compound, are observed.