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We study the magnetisation dynamics of a bulk single crystal Cr2Ge2Te6 (CGT), by means of broadband ferromagnetic resonance (FMR), for temperatures from 60 K down to 2 K. We determine the Kittel relations of the fundamental FMR mode as a function of frequency and static magnetic field for the magnetocrystalline easy -and hard -axis. The uniaxial magnetocrystalline anisotropy constant is extracted and compared with the saturation magnetisation, when normalised with their low temperature values. The ratios show a clear temperature dependence when plotted in the logarithmic scale, which departs from the predicted Callen-Callen power law fit of a straight line, where the scaling exponent n, Ku(T ) ∝ [Ms(T )/Ms(2 K)] n , contradicts the expected value of 3 for uniaxial anisotropy. Additionally, the spectroscopic g-factor for both the magnetic easy -and hard -axis exhibits a temperature dependence, with an inversion between 20 K and 30 K, suggesting an influence by orbital angular momentum. Finally, we qualitatively discuss the observation of multi-domain resonance phenomena in the FMR spectras, at magnetic fields below the saturation magnetisation.arXiv:1903.00584v2 [cond-mat.mtrl-sci]

We present measurements of ferromagnetic-resonance -driven spin pumping and inverse spin-Hall effect in NbN/Y3Fe5O12 (YIG) bilayers. A clear enhancement of the (effective) Gilbert damping constant of the thin-film YIG was observed due to the presence of the NbN spin sink.By varying the NbN thickness and employing spin-diffusion theory, we have estimated the room temperature values of the spin diffusion length and the spin Hall angle in NbN to be 14 nm and -1.1×10 -2 , respectively. Furthermore, we have determined the spin-mixing conductance of the NbN/YIG interface to be 10 nm -2 . The experimental quantification of these spin transport parameters is an important step towards the development of superconducting spintronic devices involving NbN thin films.