Electrical and magnetic characterization of Iron-Doped Gallium oxide thin films*

Fe-doped gallium oxide (Ga₂O₃) is an intriguing material to investigate due to its magnetic affinity to the material magnetite through the Verwey transition. This transition happens at a low temperature in magnetite, typically within the temperature range of 80 K to 125K. Crystal structure, magnetic properties, and resistivity change as the materials are cooled down below 120 K. The metal-to-insulator transition accompanying the Verwey transition in magnetite is currently used in nanotechnology applications and the production of magnetic nanocomposite materials. Here we study the electrical and magnetic properties at a low temperature of epitaxial Fe-doped Ga₂O₃ grown on sapphire substrates with pulsed laser deposition. For higher Fe concentration at room temperature, the material has a cubic g-phase. Ms versus T measurements performed with a MicroSense VSM from RT to 1000 K shows that this material behaves similarly to magnetite with a high-temperature transition near 900K. Additional low-temperature measurements performed with a PPMS VSM show the existence of a magnetic transition near 175K, significantly higher than the Verwey transition in magnetite. Results of additional electric characterization using a DynaCool physical property measurement system (PPMS) will be discussed in tandem with the magnetic measurement results.

*Research was sponsored by the Army Research Office and was accomplished under Grant Number W911NF-20-1-0298.