The growth and phase formation features, along with the influence of structure and morphology on the electronic, optical, and transport properties of Cr2GeC and Cr2-xMnxGeC MAX phase thin films synthesized by magnetron sputtering technique, were studied. It was found that the Cr:Ge:C atomic ratios most likely play the main role in the formation of a thin film of the MAX phase. A slight excess of carbon and manganese doping significantly improved the phase composition of the films. Cr2GeC films with a thicknesses exceeding 40 nm consisted of crystallites with well-developed facets, exhibiting metallic optical and transport properties. The hopping conduction observed in the Cr2-xMnxGeC film could be attributed to the columnar form of crystallites. Calculations based on a two-band model indicated high carrier concentrations N, P and mobility μ in the best-synthesized Cr2GeC film, suggesting transport properties close to single crystal material. The findings of this study can be utilized to enhance the growth technology of MAX phase thin films.
We report measurements of the dielectric permittivity, optical conductivity and magnetic circular dichroism (MCD) of the epitaxial Mn2GaC MAX-phase thin film in an external magnetic field of up to 200 mT, at temperatures of 296 and 140 K and 1.4 to 3.5 eV. The optical conductivity and MCD spectra show absorption peaks which are consistent with the interband electronic transitions for different positions of Mn, Ga, and C ions as confirmed by theoretical calculations of the spin-dependent density of electronic states. The well-known structural phase transition at 214 K is also seen in the changes of optical, magneto-optical and surface magnetic properties of Mn2GaC in our experiment.
In this work we report on new magneto-ellipsometry set-up that allows to grow thin films and nanostructures by ultrahigh vacuum thermal evaporation as well as to conduct in situ measurements during the growth in order to analyze and control nanostructures properties. Ellipsometry and transverse magneto-optical Kerr effect measurements can be performed in situ inside this set-up. A uniform magnetic field of high intensity (more than 1 kOe) can be applied to samples inside the vacuum chamber. Also, we report on the developed method of data interpretation that is the base of the set-up software. Thus, we present a powerful tool for nanostructures synthesis and characterization.