Orientation-dependent THz emission in non-collinear antiferromagnetic Mn3Sn and Mn3Sn-based heterostructures

Zhou, Xiaoling; Song, Bangju; Chen, Xianzhe; You, Yunfeng; Ruan, Shengping; Bai, Hua; Zhang, Wenjie; Ma, Guohong; Yao, Jianquan; Pan, Feng; Jin, Zuanming; Song, Cheng

doi:10.1063/1.5121384

Cited by 33 publications

(14 citation statements)

References 47 publications

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“…Spintronic THz emission measurements can be directly implemented on the conventional THz time-domain spectrometer driven either by femtosecond laser oscillators or amplifiers [75][76][77][78][79][80]. Typical THz emission spectrometer working in transmission mode is schematically illustrated in Fig.…”

Section: Spintronic Thz Emission Spectroscopymentioning

confidence: 99%

Spintronic terahertz emission with manipulated polarization (STEMP)

Chen

et al. 2022

Front. Optoelectron.

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Highly efficient generation and arbitrary manipulation of spin-polarized terahertz (THz) radiation will enable chiral lightwave driven quantum nonequilibrium state regulation, induce new electronic structures, consequently provide a powerful experimental tool for investigation of nonlinear THz optics and extreme THz science and applications. THz circular dichromic spectroscopy, ultrafast electron bunch manipulation, as well as THz imaging, sensing, and telecommunication, also need chiral THz waves. Here we review optical generation of circularly-polarized THz radiation but focus on recently emerged polarization tunable spintronic THz emission techniques, which possess many advantages of ultra-broadband, high efficiency, low cost, easy for integration and so on. We believe that chiral THz sources based on the combination of electron spin, ultrafast optical techniques and material structure engineering will accelerate the development of THz science and applications. Graphical Abstract

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Section: Spintronic Thz Emission Spectroscopymentioning

confidence: 99%

Spintronic terahertz emission with manipulated polarization (STEMP)

Chen

et al. 2022

Front. Optoelectron.

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“…Besides having well-defined quantum and classical Hamiltonians, as the only input required in our microscopic approach, the choice of Mn 3 Sn as an illustrative example is also motivated by recent experiments [68] observing THz emission from bilayers of Weyl AF Mn 3 Sn and SO-materials like Pt. At first sight, these observations, as well as others [69,70] involving AF spintronics THz emitters, are counter-intuitive as AF materials exhibit no net magnetization while the principal magneto-optical effects are linear in the net magnetization.…”

Section: Introductionmentioning

confidence: 99%

Quantum-classical approach to spin and charge pumping and the ensuing radiation in THz spintronics with example of ultrafast-light-driven Weyl antiferromagnet Mn$_3$Sn

Suresh¹,

Nikolić²

2022

Preprint

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The interaction of fs laser pulse with magnetic materials has been intensely studied for more than two decades in order to understand ultrafast demagnetization in single magnetic layers or THz emission from their bilayers with nonmagnetic spin-orbit (SO) materials. However, in contrast to wellunderstood spin and charge pumping by dynamical magnetization in spintronic systems driven by microwaves or current injection, analogous processes in light-driven magnets and radiation emitted by them remain largely unexplained due to multiscale nature of the problem. Here we develop a multiscale quantum-classical formalism-where conduction electrons are described by quantum master equation of the Lindblad type; classical dynamics of local magnetization is described by the Landau-Lifshitz-Gilbert (LLG) equation; and incoming light is described by classical vector potential while outgoing electromagnetic radiation is computed using Jefimenko equations for retarded electric and magnetic fields-and apply it to a bilayer of antiferromagnetic Weyl semimetal Mn3Sn, hosting noncollinear local magnetization, and SO-coupled nonmagnetic material. Our QME+LLG+Jefimenko scheme makes it possible to understand how fs laser pulse generates directly spin and charge pumping and electromagnetic radiation by the latter, including both odd and even high harmonics (of the pulse center frequency) up to order n ≤ 7. The directly pumped spin current then exert spin torque on local magnetization whose dynamics, in turn, pumps additional spin and charge currents radiating in the THz range. By switching on and off LLG dynamics and SO couplings, we unravel which microscopic mechanism contribute the most to emitted THz radiation-charge pumping by local magnetization of Mn3Sn in the presence of its own SO coupling is far more important than standardly assumed (for other types of magnetic layers) spin pumping and subsequent spin-to-charge conversion within the neighboring nonmagnetic SO-coupled material.

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“…Thus, to investigate the conductivity effect of epitaxial Fe and Pt, we choose MgO and MgAl 2 O 4 (MAO) as substrates together with an Si hemispherical lens in our THz emission set-up. So far, the scientific challenges of STEs have been addressed in various ways; optimization of STE thickness 26 , different combinations of spin source and spin sink materials 12 , ferro 27 -, ferri-and antiferromagnetic 28,29 systems as spin source, and different laser pulse excitation wavelength 30 , but not in terms of conductivity and crystal quality of the STEs.…”

Section: Introductionmentioning

confidence: 99%

Strain Engineering of Epitaxial Pt/Fe Spintronic Terahertz Emitter

Gupta,

Bagherikorani,

Mottamchetty

et al. 2021

Preprint

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Spin-based terahertz (THz) emitters, utilising the inverse spin Hall effect, are ultra-modern sources for the generation of THz electromagnetic radiation. To make a powerful emitter having large THz amplitude and bandwidth, fundamental understanding in terms of microscopic models is essential. This study reveals important factors to engineer the THz emission amplitude and bandwidth in epitaxial Pt/Fe emitters grown on MgO and MgAl 2 O 4 (MAO) substrates, where the choice of substrate plays an important role. The THz amplitude and bandwidth is affected by the induced strain in the Fe spin source layer. On the one hand, the THz electric field amplitude is found to be larger when Pt/Fe is grown on MgO even though the crystalline quality of the Fe film is superior when grown on MAO. This is because of the larger defect density, smaller electron relaxation time and lower electrical conductivity in the THz regime when Fe is grown on MgO. On the other hand, the bandwidth is found to be larger for Pt/Fe grown on MAO and is explained by the uncoupled/coupled Lorentz oscillator models. This study provides an insightful pathway to further engineer metallic spintronic THz emitters in terms of proper choice of substrate and microscopic properties of the emitter layers.

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Orientation-dependent THz emission in non-collinear antiferromagnetic Mn3Sn and Mn3Sn-based heterostructures

Cited by 33 publications

References 47 publications

Spintronic terahertz emission with manipulated polarization (STEMP)

Spintronic terahertz emission with manipulated polarization (STEMP)

Quantum-classical approach to spin and charge pumping and the ensuing radiation in THz spintronics with example of ultrafast-light-driven Weyl antiferromagnet Mn$_3$Sn

Strain Engineering of Epitaxial Pt/Fe Spintronic Terahertz Emitter

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