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

Ultrafast Spin Dynamics of Electrochemically Grown Heusler Alloy Films

“…To this end, we present the temporal variation of normalized reflectivity and Kerr rotation in Figure 6b,6c, respectively, at varying pump fluences and compare their relative variation in Figure 6d. 19 the relative variation of reflectivity is negligibly small compared to that of the Kerr rotation, implying negligible nonmagnetic contributions in the Kerr rotation data. 32,33 The comparison of the relative changes is shown for the maximum values of the variation observed for the transient Kerr rotation and reflectivity.…”

“…We examined if the Kerr rotations corresponding to the demagnetization curves originate primarily from magnetic effects or if any optical effects caused by the femtosecond laser irradiation make a significant contribution in it. To this end, we present the temporal variation of normalized reflectivity and Kerr rotation in Figure b,c, respectively, at varying pump fluences and compare their relative variation in Figure d Figure d clearly shows that the relative variation of reflectivity is negligibly small compared to that of the Kerr rotation, implying negligible nonmagnetic contributions in the Kerr rotation data. , The comparison of the relative changes is shown for the maximum values of the variation observed for the transient Kerr rotation and reflectivity.…”

“…Recently, an inverse relationship between α and τ M has been demonstrated for the half-metallic Co 2 Fe x Mn 1– x Si Heusler alloy thin films. This has been explained due to a dominating interband scattering of resistivity-like contribution in damping that leads to the inverse relationship . Hence, it is conceivable that here in the electrodeposited thin films, resistivity-like scattering is the leading mechanism for damping, i.e., excitation of interband electron and hole (e–h) pair near band gap regime of the Heusler alloy and their interactions with phonon via spin-dependent scattering speed up the damping during the picosecond dynamics.…”

“…On the other hand, TR-MOKE is an appropriate tool to study the ultrafast spin dynamics of the Heusler alloy films . Such measurements allow the determination of ultrafast demagnetization and relaxation times, magnetic anisotropy constants, and magnetic damping parameter. − Angle-dependent MOKE measurements on these films show the presence of a uniaxial anisotropy. TR-MOKE results show that femtosecond laser excitation leads to ultrafast magnetization dynamics that demonstrate a strong fluence-dependent ultrafast demagnetization and relaxation time.…”

“…This has been explained due to a dominating interband scattering of resistivity-like contribution in damping that leads to the inverse relationship. 19 Hence, it is conceivable that here in the electrodeposited thin films, resistivity-like scattering is the leading mechanism for damping, i.e., excitation of interband electron and hole (e−h) pair near band gap regime of the Heusler alloy and their interactions with phonon via spindependent scattering speed up the damping during the picosecond dynamics. This e−h pair production can be enhanced by increasing fluence, causing delayed relaxation as the excited e−h pair suffers more spin-dependent scattering with increasing fluence.…”