Structural, magnetic, and magnetotransport properties of Mn-Si films synthesized on a 4H-SiC(0001) wafer

We present a comprehensive study of the structural, magnetic, and magnetotransport properties of Mn-Si films synthesized on a 4H-SiC(0001) wafer by an annealing method. Magnetic- and fluorescence-extended x-ray-absorption fine-structure measurements reveal that the sample comprises two uncoupled magnetic phases: one is the top synthesized Mn-Si layer, which displays a Curie temperature around 300 K and magnetic anisotropy; the other one is Mn atoms, which solely incorporate on the interstitial site in the 4H-SiC lattice in the interface and show superparamagnetismlike behavior with a blocking temperature below 2 K. The magnetoresistance (MR) exhibits an interesting temperature- and field-dependent behavior. At temperatures above 100 K, the sample only exhibits a positive MR. At temperatures below 100 K, a negative MR prevails. Interestingly, at intermediate temperature of 100 K, with increasing magnetic field, a sign inversion of the MR from negative to positive is observed. The possible origin of the positive and negative MR is discussed. Furthermore, we found that the Hall effect is dominated by an anomalous Hall effect (AHE) due to side jumps at temperatures between 2 K and 100 K. However, at temperatures higher than 100 K, the AHE cannot be described with either a skew scattering or side jumps mechanism.