Terahertz Transients Emitted from La-Sr-Mn-O/Metal Nanobilayers Excited by Femtosecond Optical Pulses

We report on the generation of electromagnetic transients of picosecond duration from La-Sr-Mn-O/Au and La-Sr-Mn-O/lr nanobilayers, illuminated by femtosecond laser pulses in the presence of an external magnetic field. Fourier analysis revealed that the frequency content of these transients extended up 4 THz. The amplitude of THz transients followed the functional dependence of La-Sr-Mn-O magnetization on the magnetic field and was also tunable by varying the intensity of the optical pulses. We ascribe the observed emission of THz transients to the inverse spin Hall effect, earlier demonstrated in metallic ferromagnet/metal spintronic nanobilayers.