Frequency-Independent Terahertz Anomalous Hall Effect in DyCo5 , Co32 Fe68 , and Gd27 Fe73 Thin Films from DC to 40 THz.

The anomalous Hall effect (AHE) is a fundamental spintronic charge-to-charge-current conversion phenomenon and closely related to spin-to-charge-current conversion by the spin Hall effect. Future high-speed spintronic devices will crucially rely on such conversion phenomena at terahertz (THz) frequencies. Here, it is revealed that the AHE remains operative from DC up to 40 THz with a flat frequency response in thin films of three technologically relevant magnetic materials: DyCo5 , Co32 Fe68 , and Gd27 Fe73 . The frequency-dependent conductivity-tensor elements σxx and σyx  are measured, and good agreement with DC measurements is found. The experimental findings are fully consistent with ab initio calculations of σyx for CoFe and highlight the role of the large Drude scattering rate (≈100 THz) of metal thin films, which smears out any sharp spectral features of the THz AHE. Finally, it is found that the intrinsic contribution to the THz AHE dominates over the extrinsic mechanisms for the Co32 Fe68 sample. The results imply that the AHE and related effects such as the spin Hall effect are highly promising ingredients of future THz spintronic devices reliably operating from DC to 40 THz and beyond.

Two-gap superconductivity in Ag1-x Mo6S8 Chevrel phase.

The superconducting properties of [Formula: see text]Mo6S8 [[Formula: see text]] Chevrel phase [[Formula: see text] K] are studied on a sample compacted by spark plasma sintering. Both lower ([Formula: see text] mT) and the upper [[Formula: see text] T] critical magnetic fields are obtained from magnetization and electrical resistivity measurements for the first time. The analysis of the low-temperature electronic specific heat indicates [Formula: see text]Mo6S8 to be a two band superconductor with the energy gaps [Formula: see text] meV (95%) and [Formula: see text] meV (5%). Theoretical DFT calculations reveal a much stronger electron-phonon coupling in the studied Chevrel phase compared to earlier reports. Similar to MgB2, the Fermi surface of studied Chevrel phase is formed by two hole-like and one electron-like bands.