Longitudinal Spin Seebeck Effect in Sputtered AlCoCrCuNiFe High-Entropy Alloy Thin Films

Abstract. Spin current was generated from AlCoCrCuNiFe high-entropy alloy (HEA)/non-magnetic Pt bilayer thin films deposited on a SiO₂/Si substrate by the longitudinal spin Seebeck effect (LSSE) in combination with the inverse spin Hall effect (ISHE). AlCoCrCuNiFe (10 nm) and Pt (10 nm) thin films were fabricated using DC magnetron sputtering. During deposition of the AlCoCrCuNiFe layer, argon gas flow rates of 20 and 50 sccm were applied and subsequently annealed at 300 °C under vacuum. The results indicate that the 20 sccm condition yields a higher output voltage and exhibits a well-defined hysteresis loop under an applied magnetic field of 500 Oe, demonstrating improved spin-to-charge conversion efficiency. These findings provide valuable guidance for optimizing ferromagnetic metal–based LSSE systems for thermoelectric energy-harvesting applications.