Femtosecond formation dynamics of the spin Seebeck effect revealed by terahertz spectroscopy

Seifert, Tom S.; Jaiswal, Samridh; Barker, Joseph; Weber, Sebastian T.; Razdolski, Ilya; Cramer, Joel; Gueckstock, Oliver; Maehrlein, Sebastian F.; Nádvorník, Lukáš; Watanabe, Shigekazu; Ciccarelli, Chiara; Melnikov, Alexey; Jakob, G.; Münzenberg, Markus; Goennenwein, Sebastian T. B.; Woltersdorf, Georg; Rethfeld, Baerbel; Brouwer, Piet W.; Wolf, Martin; Kläui, Mathias; Kampfrath, Tobias

doi:10.1038/s41467-018-05135-2

Cited by 158 publications

(170 citation statements)

References 80 publications

(174 reference statements)

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“…It has been demonstrated previously that the ultrafast spin‐dependent Seebeck effect generates an out‐of‐plane spin current j s ( t ) triggered by the femtosecond laser pulses . The inverse spin Hall effect (ISHE) converts the forward and backward transient j s ( t ) from the FM layer into the transverse (in‐plane) charge current pulse j c ( t ) in the NM layers

j_{c} (t) = \frac{A F_{inc}}{d} j_{s} (t) \times λ_{rel} \tanh \frac{d_{NM}}{2 λ_{rel}} \times Θ_{SH}

where A is the absorbed fraction of the incident pump fluence ( F inc ), d is the entire metal thickness, d NM is the NM layer thickness,

λ_{rel}

is the relaxation length of the ultrafast spin current, and

Θ_{SH}

is the spin Hall angle.…”

mentioning

confidence: 99%

Terahertz Radiation Modulated by Confinement of Picosecond Current Based on Patterned Ferromagnetic Heterostructures

Jin

Zhang

Zhu

et al. 2019

Physica Rapid Research Ltrs

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The ultrashort laser excitation of nonmagnetic/ferromagnetic/nonmagnetic (NM/FM/NM) heterostructures is intensively studied as a terahertz (THz) emitter. Herein, the combined spintronic and photonic ultrathin metal heterostructures are exploited to realize actively modulated THz radiation. It is demonstrated that the THz radiation can be mediated coherently through the charge current induced by the inverse spin Hall effect (ISHE) and the built‐in transient current quasi‐simultaneously created within the striped NM/FM/NM heterostructures. The waveforms of THz radiation can be shaped by the charge current confinement effect, including the amplitude modulation and the center‐frequency shift. These findings can be utilized for device‐oriented opto‐spintronics and also extend the established THz emitter to THz modulator.

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j_{c} (t) = \frac{A F_{inc}}{d} j_{s} (t) \times λ_{rel} \tanh \frac{d_{NM}}{2 λ_{rel}} \times Θ_{SH}

where A is the absorbed fraction of the incident pump fluence ( F inc ), d is the entire metal thickness, d NM is the NM layer thickness,

λ_{rel}

is the relaxation length of the ultrafast spin current, and

Θ_{SH}

is the spin Hall angle.…”

mentioning

confidence: 99%

Terahertz Radiation Modulated by Confinement of Picosecond Current Based on Patterned Ferromagnetic Heterostructures

Jin

Zhang

Zhu

et al. 2019

Physica Rapid Research Ltrs

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“…Optical Mater. [132] The results reported by Kampfrath et al suggest that Cu-Ir alloys are promising spin-to charge-current conversion materials. The nonequilibrium electrons coming from Fe layer into the Au cap layer occupy only "sp" states having larger velocity and long lifetime.…”

Section: Wwwadvopticalmatdementioning

confidence: 99%

“…2020, 8,1900892 mentation of THz emission spectroscopy to 2D systems is a viable and credible approach to realizing such ultrafast optical control. [128][129][130][131][132][133][134][135][136][137][138][139][140][141] In the specific area of active metamaterials research, combining the electronic and magnetic control with the optical THz functionality of metamaterials promises several new possibilities for the technological utility of THz light-matter interaction. [136,137] Thus, material research by and for THz technology is one of the most exciting research fields where we can study the intrinsic nature of materials and devices.…”

Section: Wwwadvopticalmatdementioning

confidence: 99%

Terahertz Emission Functionality of High‐Temperature Superconductors and Similar Complex Systems

Rana

Tonouchi

2019

Advanced Optical Materials

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During the past two decades, terahertz (THz) science and technology have rapidly expanded in all fundamental and applied aspects of physical, chemical, and biological sciences. In physical sciences, these developments have been twofolds: i) the use of THz technology in understanding the complexities of materials and ii) the exploration of new THz functionalities of emerging materials for further advancement of THz technology. Here, the THz emission spectroscopy and the ultrafast functionality of three pillars of electronic and magnetic condensed matter systems that emerged in the following order: high-temperature superconductors, colossal magnetoresistive manganites, and magnetoelectric multiferroics are reviewed. Emission functionality refers to the emitted THz radiation that carries the information of the underlying functional property of the material such that the overall effect evolves as the THz decoding of the information in a noninvasive manner and on an ultrafast timescale.The HTSC is one of the most attractive perovskite oxides in terms of fundamental science and future applications such as in quantum information and THz devices. Superconductivity

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“…According to the Maxwell's equations, the femtosecond time‐varied current radiates electromagnetic waves in terahertz frequency range. With this method, experimental results show that the generated terahertz pulses are always linearly polarized with its electric fields perpendicular to the externally applied uniform magnetic field direction . However, up to now, it has turned out to be a very challenging task to realize arbitrary terahertz polarization control and manipulation in such FM/NM heterostructures …”

Section: Introductionmentioning

confidence: 99%

Broadband Spintronic Terahertz Emitter with Magnetic‐Field Manipulated Polarizations

Kong

Wang

et al. 2019

Advanced Optical Materials

103

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0.1-30 THz) have experienced an unprecedentedly rapid progress with potential in fundamental sciences and real applications, especially under the fast development of ultrafast laser technology. [1] Recently, terahertz technologies have also been successfully employed in laboratories as powerful tools for triggering other novel related researches and applications, such as electron accelerations, [2] strong-field nonlinear phononics, [3] nonlinear terahertz photonics, [4] nonionization imaging, [5] and so on. Significantly large potential of terahertz technology could be envisaged in its real applications such as nondestructive spectroscopy [6] and ionization-free imaging, highly sensitive sensing, [7] short-range wireless communication at terahertz bit rates, [8,9] and so on. However, hindering the development of this fascinating technology from real applications lies in the lack of highly efficient terahertz sources, versatile functional devices, and sensitive detectors, as well as compact and robust systems. Among them, terahertz sources are significantly important, especially for those integrated with flexible manipulation of terahertz polarization states. As well demonstrated, when carrying with optical spin and angular momentum, [10] it enables another freedom of utilizing terahertz waves and boosts Flexible manipulation of terahertz wave polarizations during the generation process is very important for terahertz applications, especially for the next-generation on-chip functional terahertz sources. However, current terahertz emitters cannot satisfy such demand, hence calling for new mechanisms and conceptually new terahertz sources. Here an efficient and broadband terahertz source with magnetic-field-controlled flexible switching for the polarizations between linear and elliptical states in ferromagnetic heterostructures driven by femtosecond laser pulses is demonstrated. More importantly, the chirality, azimuthal angle, and ellipticity of the generated elliptical terahertz wave can be precisely manipulated by harnessing external magnetic fields via effectively tailoring the photoinduced spin currents. Such an ultrafast photomagnetic interaction-based, magnetic-field-controlled, and broadband tunable solid-state terahertz source integrated with polarization tunability functions not only provides the capability to reveal physical mechanisms of femtosecond spin dynamics, but also demonstrates the feasibility to realize novel on-chip terahertz functional devices, boosting the potential applications for controlling elementary molecular rotations, phonon vibrations, spin precessions, high-speed communications, and accelerating the development of ultrafast terahertz optospintronics. Terahertz RadiationThe ORCID identification number(s) for the author(s) of this article can be found under https://doi.

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Femtosecond formation dynamics of the spin Seebeck effect revealed by terahertz spectroscopy

Cited by 158 publications

References 80 publications

Terahertz Radiation Modulated by Confinement of Picosecond Current Based on Patterned Ferromagnetic Heterostructures

Terahertz Radiation Modulated by Confinement of Picosecond Current Based on Patterned Ferromagnetic Heterostructures

Terahertz Emission Functionality of High‐Temperature Superconductors and Similar Complex Systems

Broadband Spintronic Terahertz Emitter with Magnetic‐Field Manipulated Polarizations

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