Magnetic and magneto-optical properties of sputtered MnGaGe films

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Abstract
The new compound manganese gallium germanide has recently been shown to be a uniaxial ferromagnet with a Curie temperature of 185°C. The easy axis of magnetization coincides with the tetragonal crystallographic c axis. Nearly completely c‐axis‐oriented films with hysteresis loops showing essentially 100% remanence normal to the film plane have been prepared by sputtering. The Curie temperature depends on the film composition. Curie temperatures as low as 110°C have been observed in nonstoichiometric films. These films have a room‐temperature coercivity of 950 Oe compared to ≥2000 Oe for stoichiometric films. At a wavelength of 6328 Å the absorption coefficient α (corrected for reflectivity) is 5.8×105 cm−1 and the room‐temperature polar Faraday rotation F is 80 000°/cm. The reflectivity R at normal incidence is 0.47. MnGaGe undergoes no phase changes before melting peritectically at 616°C and the films are stable to oxidation at temperatures well above the Curie point. The low Curie temperature combined with high remanence normal to the film plane make this material a potential candidate for magneto‐optic file applications.