Laser-induced terahertz spin transport in magnetic nanostructures arises from the same force as ultrafast demagnetization

The authors observe here that (a) laser-induced ultrafast demagnetization (UDM) of a metallic ferromagnet F has the same time evolution as (b) terahertz spin transport (TST) from F into an adjacent normal metal N. They conclude that UDM in F and TST in F|N samples are driven by the same force: (c) a generalized spin voltage, i. e. , an excess magnetization of F. One can now apply the vast knowledge of UDM to TST to significantly increase spin-current amplitudes for ultrafast spintronic applications.