Epitaxial thin films of room-temperature ferromagnetic semiconductor based on Fe2TiO5-FeTi2O5 solid solution

A series of epitaxial Fe2-xTi1+xO5 (0 <= x <= 0.7) solid solution thin films was fabricated on SrTiO3 (100) substrates by pulsed laser deposition. A (230)-oriented single phase with an orthorhombic structure was obtained within a narrow growth temperature window (850-900 degrees C). Both the semiconducting Fe1.5Ti1.5O5 and the insulating Fe1.3Ti1.7O5, as n-type oxides, showed promising thermoelectric properties with giant Seebeck coefficients up to the mV/K level. The electrical conduction in the Fe1.5Ti1.5O5 film obeyed the Arrhenius law at 200-300 K but transitioned to three-dimensional variable range hopping at 120-180 K. Furthermore, at and above room temperature (similar to 400 K), all the films (x = 0, 0.3, 0.5, and 0.7) exhibited significant ferromagnetic behavior, which was closely dependent on the different ratios of Fe2+, Fe3+, and Ti4+ ions. These results potentially lay a solid foundation for future cost-effective spintronics applications of Fe2-xTi1+xO5 films as tunable ferromagnetic semiconductors.

Automated summary

Epitaxial Fe2-xTi1+xO5 solid solution thin films were fabricated on SrTiO3 substrates with promising thermoelectric properties and significant ferromagnetic behavior, depending on the different ratios of Fe2+, Fe3+, and Ti4+ ions. The Fe1.5Ti1.5O5 film exhibited electrical conduction obeying the Arrhenius law at 200-300 K and transitioned to three-dimensional variable range hopping at 120-180 K. These results potentially provide a foundation for future spintronics applications.