Efficient THz Generation of Diabolo-Shaped Spintronic Fe/Pt Bilayer on MgO Substrate using 780-nm Pump Wavelength

Terahertz (THz) generation of spintronic heterostructures is becoming popular due to broader THz bandwidth with tunable emission amplitude and polarization [1-2]. These heterostructures typically consist of stacks of ferromagnetic (FM) and nonmagnetic (NM) thin films which generate THz radiation either by the inverse spin-Hall [3] or the interface inverse Rashba-Edelstein effect [4]. Several studies [1-2, 4] were performed which include choosing the appropriate stacks and thicknesses of NM and FM materials and suitable substrates to enhance THz emission. In most of these studies, THz generation was obtained from unstructured spintronic layers which emit electromagnetic radiation in the far-field. In this paper, we performed THz-Time Domain Spectroscopy (TDS) measurements of a diabolo-shaped Fe(3nm)/Pt(2nm) spintronic bilayer on MgO substrate using an IMRA femtolite780 laser which delivers ~100fs optical pulses at a repetition rate of 75MHz.