Enhanced laser-induced single-cycle terahertz generation in a spintronic emitter with a gradient interface

Abstract

The development of spintronic emitters of broadband THz pulses relies on designing heterostructures where processes of laser-driven spin current generation and subsequent spin-to-charge current conversion are the most efficient. An interface between ferromagnetic and nonmagnetic layers in the emitter is one of the critical elements. Here, we study experimentally single-cycle THz pulse generation from a laser-pulse excited Pt/Co emitter with a composition gradient interface between Pt and Co and compare it with the emission from a conventional Pt/Co structure with an abrupt interface. We find that the gradient interface enhances the efficiency of optics-to-THz conversion by a factor of two in a wide range of optical fluences up to 3 mJ cm${}^{-2}$. We reveal that this enhancement is caused by a pronounced increase in transmittance of the laser-driven spin-polarized current through the gradient interface compared to the abrupt one. Furthermore, we find that such a transmission deteriorates with laser fluence due to the spin accumulation effect.

References in corpus (20)

• Efficient metallic spintronic emitters of ultrabroadband terahertz radiation
• Interface-Induced Phenomena in Magnetism
• Engineering ultrafast spin currents and terahertz transients by magnetic heterostructures
• Spin Pumping and Inverse Spin Hall Effect in Platinum: The Essential Role of Spin-Memory Loss at Metallic Interfaces
• Giant room temperature interface spin Hall and inverse spin Hall effects
• Powerful and Tunable THz Emitters Based on the Fe/Pt Magnetic Heterostructure
• Broadband terahertz generation via the interface inverse Rashba-Edelstein effect
• Optimized Spintronic Terahertz Emitters Based on Epitaxial Grown Fe/Pt Layer Structures
• Scaling of Dzyaloshinskii Moriya interaction at heavy metal and ferromagnetic metal interfaces
• Spintronic Sources of Ultrashort Terahertz Electromagnetic Pulses
• Disorder Dependence of Interface Spin Memory Loss
• Principles of spintronic THz emitters
• Revealing the role of orbital magnetism in ultrafast laser-induced demagnetization in multisublattice metallic magnets by terahertz spectroscopy
• THz emission from Co/Pt bilayers with varied roughness, crystal structure, and interface intermixing
• Finite-temperature magnetism of Fe${}_x$Pd${}_{1-x}$ and Co${}_x$Pt${}_{1-x}$ alloys
• First-principles study of the spin-mixing conductance in Pt/Ni${}_{81}$Fe${}_{19}$ junctions
• THz pulses from optically excited Fe, Pt and Ta based Spintronic Heterostructures
• Origins of electromagnetic radiation from spintronic terahertz emitters: A time-dependent density functional theory plus Jefimenko equations approach
• Effect of magnetic anisotropy relaxation on laser-induced magnetization precession in thin galfenol films
• Modelling of Spintronic Terahertz Emitters as a function of spin generation and diffusion geometry