Simulation of Hot-Carrier Dynamics and Terahertz Emission in Laser-Excited Metallic Bilayers

Abstract

Metallic bilayer structures have been shown to emit strong terahertz (THz) pulses. We present a predictive multiscale mode that simulates optically induced spin-currents in a Fe/Pt-heterostructure and the emitted electric field. Electronic effects are treated on the nano scale using the Boltzmann transport equation for the dynamics of out-of-equilibrium charge carriers, numerically solved with a particle-in-cell code. The optical effects are simulated with a formalism that bridges the nanometer scale of the structure to the micrometer scale of the emitted waves. The approach helps to understand recent experimental findings on the basis of microscopic scattering effects and transport phenomena. Our theory's versatility allows it to be readily adapted to a wide spectrum of spintronic THz emitter designs. As an example, we show how the THz generation efficiency, defined as output to input power ratio, can be improved and optimized using serially stacked layers in conjunction with THz anti-reflection coatings.

References in corpus (4)

• Super-Diffusive Spin-Transport as a Mechanism of Ultrafast Demagnetization
• Perspective: Ultrafast magnetism and THz spintronics
• Raman Spectroscopy of Graphene
• Spin-orbit coupling effects on spin-dependent inelastic electronic lifetimes in ferromagnets

Cited by in corpus (11)

• Spintronic Sources of Ultrashort Terahertz Electromagnetic Pulses
• Ultrafast spin-currents and charge conversion at 3d-5d interfaces probed by time-domain terahertz spectroscopy
• Principles of spintronic THz emitters
• Transition of laser-induced terahertz spin currents from torque- to conduction-electron-mediated transport
• Spintronic THz emitters based on transition metals and semi-metals/Pt multilayers
• Origins of electromagnetic radiation from spintronic terahertz emitters: A time-dependent density functional theory plus Jefimenko equations approach
• Element resolved evidence of superdiffusive terahertz spin current arising from ultrafast demagnetization process
• Deciphering the origin of spin current in spintronic terahertz emitters and its imprint on their electromagnetic radiation via time-dependent density functional theory
• Quantum-classical approach to spin and charge pumping and the ensuing radiation in THz spintronics: Example of ultrafast-light-driven Weyl antiferromagnet Mn${}_3$Sn
• Solid-State Biased Coherent Detection of Ultra-Broadband Terahertz Pulses for high repetition rate, low pulse energy lasers
• Optimizing spin-based terahertz emission from magnetic heterostructures