Helicity-dependent THz emission induced by ultrafast spin photocurrent in nodal-line semimetal candidate Mg3Bi2

Tong, Mingyu; Hu, Yuze; Xie, Xuedong; Zhu, Xiegang; Wang, Zhenyu; Cheng, Xina; Jiang, Tian

doi:10.29026/oea.2020.200023

Cited by 17 publications

(14 citation statements)

References 38 publications

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“…19 Single-crystalline Mg 3 Bi 2 thin films deposited using molecular beam epitaxy have been reported. 20,21 However, none of the above studies were aiming for thermoelectric applications. Mg 3 Bi 2 films were deposited using direct current (dc) magnetron sputtering in an ultrahigh vacuum chamber (base pressure < 4 Â 10 À6 Pa).…”

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confidence: 99%

Epitaxial growth and thermoelectric properties of Mg3Bi2 thin films deposited by magnetron sputtering

Sadowski

Zhu

Shu

et al. 2022

Applied Physics Letters

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Mg 3 Sb 2 -based thermoelectric materials attract attention for applications near room temperature. Here, Mg-Bi films were synthesized using magnetron sputtering at deposition temperatures from room temperature to 400 C. Single-phase Mg 3 Bi 2 thin films were grown on c-planeoriented sapphire and Si(100) substrates at a low deposition temperature of 200 C. The Mg 3 Bi 2 films grew epitaxially on c-sapphire and fiber-textured on Si(100). The orientation relationships for the Mg 3 Bi 2 film with respect to the c-sapphire substrate are (0001) Mg 3 Bi 2 k(0001) Al 2 O 3 and [1120] Mg 3 Bi 2 k[1120] Al 2 O 3 . The observed epitaxy is consistent with the relatively high work of separation, calculated by the density functional theory, of 6.92 J m À2 for the Mg 3 Bi 2 (0001)/Al 2 O 3 (0001) interface. Mg 3 Bi 2 films exhibited an in-plane electrical resistivity of 34 lX m and a Seebeck coefficient of þ82.5 lV K À1 , yielding a thermoelectric power factor of 200 lW m À1 K À2 near room temperature.

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confidence: 99%

Epitaxial growth and thermoelectric properties of Mg3Bi2 thin films deposited by magnetron sputtering

Sadowski

Zhu

Shu

et al. 2022

Applied Physics Letters

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“…The burgeoning development of terahertz (THz) electromagnetic radiation has earned considerable attention for fulfilling many demands, − including THz communications, , nondestructive testing, , and chemical identification . To adapt to the modern development trend for high-performance, compact, and flexible devices, THz emitters are required to be both effective and miniaturized. − However, in existing THz emitters such as ZnTe and GaP, both the intensity and the band width of the emitted THz waves are restricted by the phase-matching condition. In addition, optical phonons and carriers within the emitter may affect the spectrum by absorbing or shielding THz waves .…”

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confidence: 99%

Ultraefficient Terahertz Emission Mediated by Shift-Current Photovoltaic Effect in Layered Gallium Telluride

Tong

et al. 2021

ACS Nano

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Generating terahertz waves using thin-layered materials holds great potential for the realization of integrated terahertz devices. However, previous studies have been limited by restricted radiation intensity and finite efficiency. Exploiting materials with higher efficiency for terahertz emission has attracted increasing interest worldwide. Herein, with visible-light excitation, a thin-layered GaTe film is demonstrated to be a promising emitter of terahertz radiation induced by the shift-current photovoltaic effect. Through theoretical calculations, a transient charge-transfer process resulting from the asymmetric structure of GaTe is shown to be the origin of an ultrafast shift current. Furthermore, it was found that the amplitude of the resulting terahertz signals can be manipulated by both the fluence of the pump laser and the orientation of the sample. Such high emission efficiency from the shift current indicates that the layered material (GaTe) is an excellent candidate for photovoltaics and terahertz emitters.

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“…Topological insulators (TIs), with strong spin–orbital coupling (SOC) and inherent spin-momentum-locked Dirac surface states (DSS), have been predicted to be one of the most effective spin-to-charge convertors. − According to previous reports, the inverse Edelstein effect (IEE) between FM and TI is orders of magnitude larger than that in conventional heavy metal (HMs), such as CoGd/Pt, Fe/Pt, and Co/Pt via the inverse-spin Hall effect (ISHE). − The latest TI-based spintronic terahertz emitter was reported in 2018, which had clarified the ultrafast dynamic process of spin-to-charge conversion between a ferromagnet and a topological insulator . Nevertheless, TI-related spintronic THz sources remain largely unexplored owing to the limited THz emission strength compared with FM/HM heterostructures, which may impede their further practical developments.…”

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confidence: 99%

Enhanced Terahertz Radiation by Efficient Spin-to-Charge Conversion in Rashba-Mediated Dirac Surface States

Tong¹,

Hu²,

Wang

et al. 2020

Nano Lett.

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The enhancement of terahertz (THz) radiation is of extreme significance for the realization of the THz probe and imaging. However, present THz technologies are far from being enough to realize high-performance and room-temperature THz sources. Fortunately, topological insulators (TIs), with spin-momentum-locked Dirac surface states, are expected to exhibit a high terahertz emission efficiency. In this work, the novel concept of a Rashba-state-enhanced spintronic THz emitter is demonstrated on the basis of ferromagnet/heavy metal/topological insulator (FM/HM/TI) heterostructure. We find that the THz emission intensity changes as a function of HM interlayer thickness, and a 1.98 times higher intensity compared to that of FM/TI can be achieved when a meticulously designed thickness of the HM layer is inserted. The improvement of terahertz radiation is ascribed to the additive effect of Rashba splitting and topological surface states at the HM/TI interface. These results offer new possibilities for realizing spintronic THz emitters in TI-based magnetic heterostructures.

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Helicity-dependent THz emission induced by ultrafast spin photocurrent in nodal-line semimetal candidate Mg3Bi2

Cited by 17 publications

References 38 publications

Epitaxial growth and thermoelectric properties of Mg3Bi2 thin films deposited by magnetron sputtering

Epitaxial growth and thermoelectric properties of Mg3Bi2 thin films deposited by magnetron sputtering

Ultraefficient Terahertz Emission Mediated by Shift-Current Photovoltaic Effect in Layered Gallium Telluride

Enhanced Terahertz Radiation by Efficient Spin-to-Charge Conversion in Rashba-Mediated Dirac Surface States

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