• Advanced Photonics
  • Vol. 5, Issue 5, 056006 (2023)
Sheng Zhang1、2、†, Yongwei Cui1、2、3, Shunjia Wang1、2, Haoran Chen1、2、3, Yaxin Liu1、2, Wentao Qin1、2、3, Tongyang Guan1、2, Chuanshan Tian1、2, Zhe Yuan4、5, Lei Zhou1、2, Yizheng Wu1、2、3、*, and Zhensheng Tao1、2、*
Author Affiliations
  • 1Fudan University, State Key Laboratory of Surface Physics, Department of Physics, Shanghai, China
  • 2Fudan University, Key Laboratory of Micro and Nano Photonic Structures, Shanghai, China
  • 3Shanghai Research Center for Quantum Sciences, Shanghai, China
  • 4Beijing Normal University, Center for Advanced Quantum Studies, Department of Physics, Beijing, China
  • 5Fudan University, Institute for Nanoelectronic Devices and Quantum Computing, Shanghai, China
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    DOI: 10.1117/1.AP.5.5.056006 Cite this Article Set citation alerts
    Sheng Zhang, Yongwei Cui, Shunjia Wang, Haoran Chen, Yaxin Liu, Wentao Qin, Tongyang Guan, Chuanshan Tian, Zhe Yuan, Lei Zhou, Yizheng Wu, Zhensheng Tao. Nonrelativistic and nonmagnetic terahertz-wave generation via ultrafast current control in anisotropic conductive heterostructures[J]. Advanced Photonics, 2023, 5(5): 056006 Copy Citation Text show less

    Abstract

    Precise and ultrafast control over photo-induced charge currents across nanoscale interfaces could lead to important applications in energy harvesting, ultrafast electronics, and coherent terahertz sources. Recent studies have shown that several relativistic mechanisms, including inverse spin-Hall effect, inverse Rashba–Edelstein effect, and inverse spin-orbit-torque effect, can convert longitudinally injected spin-polarized currents from magnetic materials to transverse charge currents, thereby harnessing these currents for terahertz generation. However, these mechanisms typically require external magnetic fields and exhibit limitations in terms of spin-polarization rates and efficiencies of relativistic spin-to-charge conversion. We present a nonrelativistic and nonmagnetic mechanism that directly utilizes the photoexcited high-density charge currents across the interface. We demonstrate that the electrical anisotropy of conductive oxides RuO2 and IrO2 can effectively deflect injected charge currents to the transverse direction, resulting in efficient and broadband terahertz radiation. Importantly, this mechanism has the potential to offer much higher conversion efficiency compared to previous methods, as conductive materials with large electrical anisotropy are readily available, whereas further increasing the spin-Hall angle of heavy-metal materials would be challenging. Our findings offer exciting possibilities for directly utilizing these photoexcited high-density currents across metallic interfaces for ultrafast electronics and terahertz spectroscopy.
    Ex(ω)=Z(ω)e0dEACdzβ0jz(z,ω),

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    σ=[σ000σ000σ].

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    Z(ω)=Z0nair(ω)+nTiO2(ω)+Z0·0ddzσ(z,ω),

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    jz(z)=ji(dNM)sinh(zdEACλEAC)sinh(dEACλEAC),

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    ji(dNM)FabsdNMω0tanh(dNM2λNM).

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    Ex(ω)FabsdNMω0·Z0nair(ω)+nTiO2(ω)+Z0·(σEACdEAC+σNMdNM)·tanh(dNM2λNM)·tanh(dEAC2λEAC),

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    Fabs=F·(1R1)·(1R2)·eαNMdNM·(1eαEACdEAC),

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    Sheng Zhang, Yongwei Cui, Shunjia Wang, Haoran Chen, Yaxin Liu, Wentao Qin, Tongyang Guan, Chuanshan Tian, Zhe Yuan, Lei Zhou, Yizheng Wu, Zhensheng Tao. Nonrelativistic and nonmagnetic terahertz-wave generation via ultrafast current control in anisotropic conductive heterostructures[J]. Advanced Photonics, 2023, 5(5): 056006
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