Excimer-laser-annealing-induced crystallization and atomic ordering of Co2Mn0.5Fe0.5Ge Heusler alloy thin films for spintronic applications

Abstract

Magnetic Heusler alloys are highly attractive for spintronics; however, realizing their full potential requires high-temperature annealing, which is often incompatible with practical device fabrication. Excimer laser annealing (ELA) potentially addresses this temperature constraint by making use of the short annealing time and temperature gradient along the depth direction. We investigated the effect of ELA on Co2Mn0.5Fe0.5Ge half-metallic Heusler-alloy thin films and demonstrated that ELA successfully induces crystallization and B2 atomic ordering. Optimized ELA condition using low fluence with a high number of laser irradiations achieved reduced resistivity and negative anisotropic magnetoresistance, indicating improved atomic ordering and high spin polarization, while maintaining flatness of the films. These findings establish ELA as a viable annealing method for integrating high-performance Heusler alloys into the device structure with strict thermal budget. Moreover, ELA offers additional advantages such as enhanced throughput and selective area annealing, thereby broadening the scope of Heusler-alloy applications in spintronic devices.