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

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 IrMn3/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 IrMn3 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.

Automated summary

The experimental investigation of ultrafast electro-optical properties in magnetic materials shows great potential for spintronic optoelectronic devices. A spintronic terahertz emitter was constructed using time-resolved terahertz emission spectroscopy with an IrMn3/Ni-Fe heterojunction. The spin current generated in the Ni-Fe layer is converted into a charge current by the IrMn3 layer, allowing for timely recording of the terahertz emission.