Thickness dependence of the spintronic terahertz emission from Ni/Pt bilayer grown on MgO via electron beam deposition

We report on the spintronic terahertz (THz) emission from a Ni/Pt bilayer on MgO grown via electron beam deposition. The films were grown with varying Ni thicknesses with a constant Pt thickness. The nominal Ni thickness values of 3, 5, 7, 9, 15, and 23 nm exhibited thickness-dependence of the THz emission intensities which was well-fitted with a model by Torosyan et al. Thickness-dependence was also observed for the peak frequencies and bandwidth characteristics. These results are consistent with previously reported MBE-grown ferromagnetic/nonmagnetic metal spintronic THz emitters utilizing the inverse spin-Hall effect.