Terahertz Generation via Picosecond Spin-to-Charge Conversion in IrMn3/Ni-Fe Heterojunction

Abstract

Experimental investigations of ultrafast electro-optical properties in magnetic materials manifest their great potential for emerging spintronic optoelectronic devices. Here, using time-resolved terahertz emission spectroscopy, we construct a spintronic terahertz emitter consisting of an IrMn 3/Ni−Fe heterojunction. A femtosecond spin current pulse is generated in the thin film of the Ni−Fe layer when it absorbs a femtosecond laser pulse, and then the spin current is converted into a transient charge current by the metallic IrMn 3 layer on picosecond timescales. We timely record the terahertz emission associated with this ultrafast conversion process by means of electro-optic sampling. Besides, the spin-to-charge conversion efficiency of the IrMn3/Ni−Fe heterojunction is determined via quantitative analysis of the spin torque ferromagnetic resonance results. We have both optically verified and electrically studied the spin-to-charge conversion of the IrMn3/Ni−Fe heterojunction. Our results enlarge the material choice range of spintronic terahertz emitters, which may promote further investigations of ultrafast spin-to-charge conversion in different heterojunction materials