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

Abstract

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.