Structural and Transport Characterization of Ti and La0.7Sr0.3MnO3 Thin Films to Become Non-Local Spin Valves

Abstract

Structural and transport characterization of thin films is important for the fabrication and performance of non-local spin valves, NLSVs, especially when new materials are integrated into the device. In the present study, thin films of one non-magnetic metal, Ti, and one ferromagnetic oxide, La_0.7Sr_0.3MnO₃ (LSMO), were characterized to illustrate the general process of preparing and analyzing thin films for NLSVs. NLSVs allow for the material properties of spin polarization and spin diffusion length to be measured. These properties have applications in expanding the efficiency of spintronic devices. For structural characterization, the thickness of each thin film was measured using x-ray reflectometry. For transport characterization, the resistance of each thin film was measured over a range of temperatures. The resistance of the thin film was related to resistivity using the Van der Pauw equation. The relationship between resistivity and temperature provides insight into the purity of the thin film through the residual resistivity ratio, RRR, and the Curie temperature, T_c, (for ferromagnetic materials). A comparison of the properties of fabricated LSMO nanowires to their starting films show a similar T_c and RRR, suggesting that the quality of the material was not compromised during the fabrication process.