The role of topological spin defects in magnetotransport ofCrO2

Abstract

We investigated the temperature dependence of the resistivity for a wide temperature range forCrO2(100) epitaxial films. Thetemperature derivative dρ/dT definitely shows the same character as the magnetic heat capacity anomaly inthe critical regime even in a finite magnetic field and the critical exponents(α) deduced are consistent with those of 3D Heisenberg ferromagnets. In addition, we foundthat the spin dependent resistivity over a wide temperature range can be simplyproportional to the density of diluted topological spin defects (Skyrmion strings) suggestingthat those nontrivial topological defects scatter conduction electrons just like impurities.The excitation energy of such topological defects is quite comparable to that obtained byanomalous Hall effect analysis of the Ye et al model based on the Berry phase. Theoverall results give a simple picture wherein the density of the topological defectscan be a dominant mechanism of resistivity, like the anomalous Hall effect. Theresults concerning the critical exponent analysis and intuition concerning scatteringcentres of magnetic disorder suggest a specific picture of the Fisher–Langer model.