Resistance anomaly and linear magnetoresistance in thin flakes of itinerant ferromagnet Fe₃GeTe₂

Abstract Research interests in recent years have expanded into quantum materials that display novel magnetism incorporating strong correlations, topological effects, and dimensional crossovers. The Fe 3 GeTe 2 represents such a two-dimensional van der Waals platform exhibiting itinerant ferromagnetism with many intriguing properties. Up to now, most electronic transport studies on Fe 3 GeTe 2 have been limited to its anomalous Hall responses while the longitudinal counterpart (such as magnetoresistance) remains largely unexplored. Here, we report a few unusual transport behaviors on thin flakes of Fe 3 GeTe 2 . Upon cooling to the base temperature, the sample develops a resistivity upturn that shows a crossover from a marginally -ln T to a - T 1/2 dependence, followed by a lower-temperature deviation. Moreover, we observe a negative and nonsaturating linear magnetoresistance when the magnetization and the external field is parallel (or antiparallel). The slope of the linear magnetoresistance also shows a nonmonotonic temperature dependence. We deduce an anomalous contribution to the magnetoresistance at low temperatures with a scaling function proportional - HT 1/2 , as well as a temperature-independent linear term. Possible mechanisms that could account for our observations are discussed.