Spin curvature induced resistivity in epitaxial half-metallic CrO2 thin films

Abstract

Spin configuration inside a ferromagnetic metal influences its magnetoresistive behavior. The local spin curvature induces excess resistivity from the homogeneous ferromagnetic state. In this work, we characterize the spin curvature induced resistivity in epitaxial half-metallic CrO₂ nanowires with 100% spin polarization. We control the magnitude of the spin curvature by introducing different geometric notches along the edge of the wire and applying an external magnetic field. Through magnetoresistance measurements and micromagnetic simulations, we uncover an empirical relationship between the spin curvature and the induced resistivity in this archetypal half-metallic solid. This relationship provides a quantitative method to calculate the resistance of magnetic domain walls or other spin textured states. We also study the influence of the thermal effect on the spin curvature induced resistivity across temperatures ranging from 10 K to 250 K. Thermal magnons worsen spin asymmetry considerably and suppress spin curvature induced resistivity at temperatures much lower than the ferromagnetic ordering temperature T_c.