Micromagnetism and magnetotransport properties of micron-sized epitaxial CrO2(100) wires

We report a detailed study of the magnetic domain configurations and the magnetization reversal in epitaxial CrO2(100) wires (0.5-5 mu m widths) patterned along different crystallographic directions. Magnetic force microscopy imaging in zero field reveals single domain states for wires fabricated along the magnetic easy axis, while wires perpendicular to the magnetic easy axis exhibit a stripe domain configuration. The behavior in an applied field and the switching of the magnetization is probed by magnetoresistance (MR) measurements. Depending on the orientation of the wire with respect to the easy and hard magnetocrystalline anisotropy axes and the field direction, distinctly different reversal modes are observed including inhomogeneous magnetization configurations. These modes and configurations can be explained taking into account the interplay between the different anisotropy terms. MR measurements at variable temperatures demonstrate that the low temperature MR response is dominated by intergrain-tunneling magnetoresistance, while at elevated temperatures it is superseded by the anisotropic MR.