Fachgruppe Nanostrukturierte Materialien    

A spintronic bilayer structure, which consists of 2-nm Fe and 3-nm Pt epitaxial grown on 500-um MgO substrate, was investigated as a terahertz (THz) source for different optical pump wavelengths and various average excitation power levels. By using this optimized Fe/Pt bilayer as the emitter in a standard THz time-domain emission spectroscopy setup, we demonstrate the efficient spintronic generation of pulsed THz radiation at 400-nm, ~800-nm, and 1550-nm excitation wavelengths even with relatively low average excitation power. The results show that the Fe/Pt on MgO is a versatile spintronic THz radiation source, as it exhibits fairly the same THz emission efficiency per average pump power across a wide range of femtosecond laser source wavelengths, from near-infrared and even up to the visible. Moreover, comparison of its THz emission performance with that of a dipole-type LT-GaAs photoconductive antenna shows that the spintronic epitaxial bilayer is a convenient alternative THz emitter.