Anomalous low-field magnetoresistance in Fe3Ga4 single crystals

Fe3Ga4 possesses a helical spin spiral with a complex competition between ferromagnetic and antiferromagnetic ground states. This competition generates multiple metamagnetic transitions that are governed by both the applied magnetic field and temperature. At intermediate temperatures between T1 (68 K) and T2 (360 K), the ferromagnetically aligned spins transition to an antiferromagnetic spin spiral. In this study, magnetoresistance (MR) measurements are performed on an aligned single crystal and compared to magnetization properties in order to gain insight into the unique alignment of the spins. The high-field MR is positive at low temperatures, indicating cyclotronic behavior, and negative at high temperatures from electron–magnon scattering. Of particular significance is a large anomalous positive MR at low fields, possibly due to emergent spin fluctuations, thus prompting further exploration of this multifaceted material.