Co${}_2$FeAl full Heusler compound based spintronic terahertz emitter

Abstract

To achieve a large terahertz (THz) amplitude from a spintronic THz emitter (STE), materials with 100\% spin polarisation such as Co-based Heusler compounds as the ferromagnetic layer are required. However, these compounds are known to loose their half-metallicity in the ultrathin film regime, as it is difficult to achieve L2${}_1$ ordering, which has become a bottleneck for the film growth. Here, the successful deposition using room temperature DC sputtering of the L2${}_1$ and B2 ordered phases of the Co${}_2$FeAl full Heusler compound is reported. Co${}_2$FeAl is used as ferromagnetic layer together with highly orientated Pt as non-ferromagnetic layer in the Co${}_2$FeAl/Pt STE, where an MgO(10 nm) seed layer plays an important role to achieve the L2${}_1$ and B2 ordering of Co${}_2$FeAl. The generation of THz radiation in the CFA/Pt STE is presented, which has a bandwidth in the range of 0.1-4 THz. The THz electric field amplitude is optimized with respect to thickness, orientation, and growth parameters using a thickness dependent model considering the optically induced spin current, superdiffusive spin current, inverse spin Hall effect and the attenuation of THz radiation in the layers. This study, based on the full Heusler Co${}_2$FeAl compound opens up a plethora possibilities in STE research involving full Heusler compounds.

7 pages, 4 figures

References in corpus (4)

• Super-Diffusive Spin-Transport as a Mechanism of Ultrafast Demagnetization
• Powerful and Tunable THz Emitters Based on the Fe/Pt Magnetic Heterostructure
• Spin-orbit torques in heavy metal/ferromagnet bilayers with varying strength of interfacial spin-orbit coupling
• Substituting the main group element in cobalt - iron based Heusler alloys: Co${}_2$FeAl${}_{1-x}$Si${}_x$

Cited by in corpus (9)

• Spintronic Sources of Ultrashort Terahertz Electromagnetic Pulses
• Inertial spin dynamics in epitaxial cobalt films
• Atomic disorder and Berry phase driven anomalous Hall effect in Co2FeAl Heusler compound
• Transition of laser-induced terahertz spin currents from torque- to conduction-electron-mediated transport
• Spin-voltage-driven efficient terahertz spin currents from the magnetic Weyl semimetals Co${}_2$MnGa and Co${}_2$MnAl
• Spintronic THz emitters based on transition metals and semi-metals/Pt multilayers
• Direct evidence of terahertz emission arising from anomalous Hall effect
• Element resolved evidence of superdiffusive terahertz spin current arising from ultrafast demagnetization process
• Magnetization switching in the inertial regime