Crystalline orientation-dependent anisotropic magnetoresistance effect in half-metallic ferromagnet of bulk single crystal Co2MnGe Heusler alloy

Anisotropic magnetoresistance (AMR) and temperature dependence of electronic resistivity along the [100], [011], and [111] orientations were investigated in the bulk single crystal of Co2MnGe, which has been considered as one of the typical half-metallic ferromagnets (HMFs). Negative AMR was observed for all crystal orientations across temperatures ranging from 6 to 300 K, consistent with theoretical predictions for HMFs, and the values were small, with in the range of 0.08%–0.3% exhibiting no sensitivity to temperature. Temperature-dependent resistivity revealed that the electron–phonon scattering was the dominant mechanism across the entire measured temperature range, exhibiting T5 behavior at low temperatures and linear temperature behavior at higher temperatures for all crystal orientations. The absence of electron–magnon scattering and scattering process of s↑ → d↓ further supports the half-metallic nature of Co2MnGe.