Domain structures and the influence of current on domains and domain walls in highly spin-polarized CrO2 wire elements

Abstract

We present a detailed study of the equilibrium magnetization configurations and their response to injected current pulses in microstructured CrO2 wire elements. Using magnetic force microscopy, we determine that the magnetic domain structure of CrO2 wires strongly depends on the wire geometry, in particular, on the wire width and the wire orientation with respect to the magnetocrystalline anisotropy axes. Depending on the wire geometry and the orientation of the initialization magnetic field used, single domain or closure domain configurations have been observed. The domain widths depend on the wire width and are very well reproduced by analytical calculations, as well as by micromagnetic simulations. Currents of up to 5.1 x 10 power 10 A/m power 2 were injected into the CrO2 wires at room temperature and found to alter their magnetic domain configuration. Temperature-dependent resistance measurements during the current pulse injection reveal the importance of Joule heating, which can raise the sample temperature above the Curie temperature of CrO2 for pulses injectedat room temperature. Low-temperature magnetoresistance measurements reveal a strong reduction in the domain wall depinning field even for injected current densities as low as 10 power 10 A/m power 2.