UC Riverside

The recent advent of 2D atomically layered ferromagnetic materials has brought a great deal of excitement in condensed matter physics and materials science. Despite the intense ongoing research, the physics of many fascinating phenomena is still not completely understood. We explore several physical properties of a special type of 2D ferromagnets: Fe3GeTe2 (FGT) and Fe5Ge2Te2 (FG2T) in my dissertation research. FGT and FG2T are layered metallic ferromagnets with the phase transition from paramagnetic to ferromagnetic phase near room temperature, the highest among other known 2D magnets. The high Curie temperature, strong magnetic anisotropy, and the metallicity make them the best candidate materials for the next generation of high-density memory and logic devices.In this dissertation, I will present my study of the 2D FGT and FG2T nanodevices from the perspective of magneto-transport measurements. I present and discuss the fabrication process challenges in fabricating FGT and FG2T flakes with nanometer dimensions, the layer dependence of the low-temperature Kondo behaviors and the linear magnetoresistance, and the layer dependence of the perpendicular magnetic anisotropy field, Curie temperature, longitudinal and anomalous Hall conductivities. In addition, I will discuss the effect of the spin current generated in Pt on the FGT magnetization reversal due to the damping-like spin-orbit torque. Also, we quantify the magnitude of the SOT effect by measuring the second harmonic Hall responses as the applied magnetic field rotates the FGT magnetization in the plane.