Growth temperature-controlled Gilbert damping and anisotropies in PLD grown epitaxial Co2FeSi Heusler alloy thin film

Abstract

The utilization of spin rather than charge as a functional aspect in the electronic devices will result in an energy-efficient, thermally stable, and fast operation. Cobalt-based Heusler alloy Co2FeSi (CFS) offers excellent possibilities due to its high curie temperature, large spin polarization, and low Gilbert damping (α). Small damping makes the alloy fascinating for spin transfer torque magnetoresistive random-access memory (STT-MRAM) devices where a low α causes a low value of switching current. The present investigation explored the effect of deposition temperature on the chemical, structural and magnetic properties of the pulsed laser deposition grown single-crystal CFS film of thickness 50 nm on a lattice-matched (001) MgO substrate. The XRD data suggest that Co site atomic ordering and overall film crystallinity improved with temperature, resulting in a minimal value of α obtained from ferromagnetic resonance (FMR) experiment in the film grown at 600°C. The azimuthal angular variation (φ) of FMR field data gives a fourfold anisotropy pattern that confirms the single-crystal CFS film epitaxially grown on the MgO substrate. Two in-plane anisotropies, namely cubic (four-fold) and uniaxial, were obtained in all the samples. This investigation is crucial in the fabrication of fast spintronics based memory and processing devices.