Terahertz emission from LaAlO3/SrTiO3 heterostructures pumped with femtosecond laser

Since the discovery of the ultrafast demagnetization of the ferromagnetic metal, the spin degree of electronsis gradually used to generate terahertz radiation. The terahertz radiation generated by the inverse Rashba-Edelstein effect was confirmed first at the interface of Ag/Bi. However, the spin-to-charge conversion efficiencyof the LaAlO3/SrTiO3 interface is one order of magnitude lager than that of the Ag/Bi interface underequilibrium or quasi-equilibrium condition. Whether the LaAlO3/SrTiO3 heterostructures can be used to convertspin current to generate terahertz radiation remains to be systemically studied. In this work, we fabricate theNiFe/LaAlO3//SrTiO3 heterostructures and investigate the generation of terahertz radiation by femtosecondlaser pumping and its dependence of the magnetic field direction. We change the thickness of the LaAlO3 toshow the applicability of the superdiffusive spin transport model and optical transmission model. We find themultireflections at the LaAlO3/SrTiO3 interface weaken the terahertz radiation intensity. This work providesexperimental and theoretical support for further optimizing the generation of terahertz electromagnetic waves