Enhanced performance of spintronic terahertz emitters based on defect engineering

Sascha Keller, Dennis M. Nenno, Garik Torosyan, Laura Scheuer, Marco Battiato, Jörg Losch, Alexander Brodyanski, Rolf H. Binder, Hans C. Schneider, Rene Beigang, Evangelos Th. Papaioannou

Published 2019-01-28Version 1

Spintronic ferromagnetic/non-magnetic heterostructures are novel sources for the generation of THz radiation based on the spin-to-charge conversion in the films. The key technological and scientific challenge of THz spintronic emitters is to increase their low intensity and frequency bandwidth. Our work reveals the factors to engineer both by introducing the scattering lifetime and the inteface transmission for spin polarized, non-equilibrium electrons. We resolve the role played by the electron-defect scattering lifetime on the spectral shape and the interface transmission on the THz amplitude and how this is linked to structural defects of bilayer emitters. The results of our study define a roadmap of the properties of the emitted as well as the detected THz-pulse shapes and spectra that is essential for future applications of metallic spintronic THz emitters.