Search

We describe the comprehensive characterization of GaMnAs epitaxial thin films and magnetic tunnel junctions (MTJ) by complementary techniques ranging from high-resolution imaging to magnetometry, magnetotransport, time-resolved magneto-optics, and coplanar broadband ferromagnetic resonance (FMR). Magnetometry and magnetotransport on macroscopic samples allow deriving the saturation magnetization and quasi-static reversal fields. Perpendicular transport experiments on patterned MTJ pillars further reveal the tunneling magnetoresistance ratio. Additionally the precessional dynamics are characterized by time-resolved magneto-optics and broadband network analyzer FMR yielding the effective Gilbert damping and the sample anisotropies. The combination of the different techniques allows a comprehensive characterization of the key magnetostatic and dynamic material parameters of GaMnAs-based thin films and devices. [ABSTRACT FROM AUTHOR]

Chromium dioxide (CrO 2) nanowires with their half-metallic ferromagnetic properties have shown great promise in spintronics applications. However, growth of such wires remains challenging. We used the Selective Area growth method to fabricate high quality epitaxial CrO 2 wires on a TiO 2 substrate, using trenches oriented both along the substrate [001] c -axis and along the [010] b -axis, which are the magnetically easy and hard axis of the wire, respectively. We investigated the morphology of the wires by high-resolution transmission electron microscopy (TEM) and measured their physical properties, in particular magnetoresistance (MR) and the Anomalous Hall Effect (AHE). TEM images showed that the morphology of the wires grown along the two axes are very different. MR data show very sharp switching for c -axis grown wires (the easy axis), even for quite large wire widths. The AHE is found to be different for c -axis wires and b -axis wires, which we argue to be due to a different wire morphology on the nanoscale. • Selective Area Growth can produce high-quality nanowires of CrO 2. • Selective Area grown CrO 2 nanowires are different from wires etched out of a film • Substrate mismatch leads to morphologically different wires for different surface directions. • The Anomalous Hall coefficient is diferent for different wire orientations. [ABSTRACT FROM AUTHOR]