Unconventional magnetoresistive behavior near magnetic compensation temperature in ferrimagnetic Mn_2.21Ru_0.86Ga films

Ferrimagnets with magnetic compensation temperature (Tcomp) around room temperature are desirable due to their potential applications in low-energy consuming and high-frequency spintronic devices. In this study, the Tcomp of ferrimagnetic Mn2.21Ru0.86Ga (MRG) is tuned to near room temperature by strain. Moreover, we observed unconventional magnetoresistance behaviors for MRG-based Hall bar devices near Tcomp. First-principles calculations suggest two kinds of Mn moments, which lead to two anomalous Hall channels with opposite signs and consequently correspond to the peak structure and triple loops of the anomalous Hall effect loops. The unconventional temperature dependence of longitudinal resistivity is caused by the combined effects of two types of Mn moments and the anisotropic magnetoresistance of the MRG film. Interestingly, the spontaneous Hall angle of the MRG film is calculated to be ∼2.2%, which is one order of magnitude larger than those of other 3d ferromagnets. Therefore, our study demonstrates MRG to be a ferrimagnet with the Tcomp near room temperature, which enables its potential applications in spintronic devices.