Magnetic- and Spin-Gapless-Related Transport Properties in Sputtered Mn₂CoGa Thin Films

Spin-gapless semiconductors (SGS) are highly attractive for spintronics applications due to their unique spin-polarized band structure. In this study, the potential SGS candidate of Mn2CoGa alloy is focused on by growing thin films using magnetron sputtering on Si(001)/SiO2 substrates. By applying appropriate heat treatment, the Mn2CoGa thin films can crystallize into the expected Heusler structure, as confirmed by the dominant (220) peak observed in X-ray diffraction. These films exhibit soft magnetized behavior, with a saturation magnetization of approximately 1.86 mu(B) f.u.(-1) at 10 K. This value deviates slightly from the theoretical prediction, indicating the presence of antisite disorder within the film. The resistivity curve shows a negative temperature coefficient, which is attributed to the strong electron-electron interaction that is also connected to the disorder. Despite the presence of disorder, positive variation and sign reversal of the magnetoresistance are observed, along with a nearly vanishing anomalous Hall effect, both of which are typical characteristics of SGS. Compared to bulk Mn2CoGa, the carrier concentration is larger and the mobility is lower in the film, while similar temperature dependences are observed.