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Condensed Matter, Mesoscale and Nanoscale Physics, cond-mat.mes-hall, Condensed Matter, Materials Science, cond-mat.mtrl-sci
Abstract:
Magnetic Weyl semimetals are an emerging material class that combines
magnetic order and a topologically non-trivial band structure. Here, we study
ultrafast optically driven spin injection from thin films of the magnetic Weyl
semimetals Co2MnGa and Co2MnAl into an adjacent Pt layer by means of
terahertz emission spectroscopy. We find that (i) Co2MnGa and Co2MnAl are
efficient terahertz spin-current generators reaching efficiencies of typical
3d-transition-metal ferromagnets such as Fe. (ii) The relaxation of the spin
current provides an estimate of the electron-spin relaxation time of Co2MnGa
(165 fs) and Co2MnAl (102 fs), which is comparable to Fe (92 fs). Both
observations are consistent with a simple analytical model and highlight the
large potential of magnetic Weyl semimetals as spin-current sources in
terahertz spintronic devices. Finally, our results provide a strategy to
identify magnetic materials that provide maximum spin current amplitudes for a
given deposited optical energy density.
