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Engineering Co 2 MnAl x Si 1− x Heusler Compounds as a Model System to Correlate Spin Polarization, Intrinsic Gilbert Damping, and Ultrafast Demagnetization
Author(s) -
Guillemard Charles,
Zhang Wei,
Malinowski Gregory,
de Melo Claudia,
Gorchon Jon,
PetitWatelot Sebastien,
Ghanbaja Jaafar,
Mangin Stéphane,
Le Fèvre Patrick,
Bertran Francois,
Andrieu Stéphane
Publication year - 2020
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201908357
Subject(s) - condensed matter physics , spintronics , spin polarization , magnetization , magnetization dynamics , demagnetizing field , materials science , ferromagnetism , ultrashort pulse , dissipation , polarization (electrochemistry) , physics , electron , magnetic field , laser , optics , quantum mechanics , chemistry
Engineering of magnetic materials for developing better spintronic applications relies on the control of two key parameters: the spin polarization and the Gilbert damping, responsible for the spin angular momentum dissipation. Both of them are expected to affect the ultrafast magnetization dynamics occurring on the femtosecond timescale. Here, engineered Co 2 MnAl x Si 1‐ x Heusler compounds are used to adjust the degree of spin polarization at the Fermi energy, P , from 60% to 100% and to investigate how they correlate with the damping. It is experimentally demonstrated that the damping decreases when increasing the spin polarization from 1.1 × 10 −3 for Co 2 MnAl with 63% spin polarization to an ultralow value of 4.6 × 10 −4 for the half‐metallic ferromagnet Co 2 MnSi. This allows the investigation of the relation between these two parameters and the ultrafast demagnetization time characterizing the loss of magnetization occurring after femtosecond laser pulse excitation. The demagnetization time is observed to be inversely proportional to 1 – P and, as a consequence, to the magnetic damping, which can be attributed to the similarity of the spin angular momentum dissipation processes responsible for these two effects. Altogether, the high‐quality Heusler compounds allow control over the band structure and therefore the channel for spin angular momentum dissipation.