Efficient Co/Pt THz spintronic emitter with tunable polarization

Abstract

We report on the design of a spintronic emitter based on the Pt(3 nm)/Co(3 nm) structure, which enables the control over terahertz radiation polarization. Utilizing the field-induced magnetization rotation that takes place at low magnetic fields of up to 250 Oe at room temperature, we have achieved the full range of terahertz polarization rotation from 0° to 360°. This rotation became possible due to the uniaxial magnetic anisotropy induced in the plane of the cobalt film during its fabrication. We evaluated the efficiency of the Co/Pt structure in generating terahertz radiation and found that the terahertz pulse energy flux reaches ∼160 nJ/cm2 at an excitation flux of 4 mJ/cm2.