Magnetic and spin-dependent transport properties of reactive sputtered epitaxial Ti1−xCrxN films

Abstract

Reactive-sputtered epitaxial Ti1−xCrxN films are ferromagnetic in the range of 0.17⩽x⩽0.51 due to the Cr–N–Cr double-exchange interaction below the Curie temperature (TC). The TC first increases, then decreases as x increases, and a maximum of 120K appears at x=0.47. All of the films are metallic with a transition near TC. A resistivity minimum ρmin is observed below 60K in the films with 0.10⩽x⩽0.51 due to the effects of the weak localization and electron–electron interaction. The negative magnetoresistance (MR) is caused by the double-exchange interaction below TC and the weak localization can also contribute to MR below Tmin where ρmin appears. The x-dependent electron carrier densities reveal that the ferromagnetism is not from the carrier-mediated mechanism. The anomalous Hall resistivity follows the relation of ρxyA∝ρxx2, which is from the side-jump mechanism.