Ultrafast demagnetization mechanism in half-metallic Heusler alloy thin films controlled by the Fermi level

Abstract

The electronic band structure-controlled ultrafast demagnetization mechanism in Co2FexMn1-xSi Heusler alloy is underpinned by systematic variation of composition. We find the spin-flip scattering rate controlled by spin density of states at Fermi level is responsible for non-monotonic variation of ultrafast demagnetization time (τM) with x with a maximum at x = 0.4. Furthermore, Gilbert damping constant exhibits an inverse relationship with τM due to the dominance of inter-band scattering mechanism. This demonstrates a connection between ultrafast demagnetization and magnetic damping based on Fermi level position in this Heusler alloy system.