Tunneling Magnetoresistance and Spin-Dependent Diode Performance in Fully Epitaxial Magnetic Tunnel Junctions With a Rocksalt ZnO/MgO Bilayer Tunnel Barrier

Metal/insulator/metal (MIM) tunnel diodes are promising for high-frequency rectifier systems, such as for energy harvesting in the infrared-to-terahertz range, where typical semiconductor devices cannot operate. For practical applications, though, better rectification is needed. The authors fabricate fully epitaxial Fe/ZnO/MgO/Fe tunnel junctions exhibiting 96% magnetoresistance at room temperature, as well as greatly enhanced rectification performance, due to magnon excitations at the Fe/barrier interfaces. This is an exciting result for energy harvesting at longer wavelengths.