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Ultrafast photoinduced band splitting and carrier dynamics in chiral tellurium nanosheets

Author

Listed:
  • Giriraj Jnawali

    (University of Cincinnati)

  • Yuan Xiang

    (The George Washington University)

  • Samuel M. Linser

    (University of Cincinnati)

  • Iraj Abbasian Shojaei

    (University of Cincinnati)

  • Ruoxing Wang

    (Purdue University)

  • Gang Qiu

    (Purdue University)

  • Chao Lian

    (University of California, Riverside)

  • Bryan M. Wong

    (University of California, Riverside)

  • Wenzhuo Wu

    (Purdue University)

  • Peide D. Ye

    (Purdue University)

  • Yongsheng Leng

    (The George Washington University)

  • Howard E. Jackson

    (University of Cincinnati)

  • Leigh M. Smith

    (University of Cincinnati)

Abstract

Trigonal tellurium (Te) is a chiral semiconductor that lacks both mirror and inversion symmetries, resulting in complex band structures with Weyl crossings and unique spin textures. Detailed time-resolved polarized reflectance spectroscopy is used to investigate its band structure and carrier dynamics. The polarized transient spectra reveal optical transitions between the uppermost spin-split H4 and H5 and the degenerate H6 valence bands (VB) and the lowest degenerate H6 conduction band (CB) as well as a higher energy transition at the L-point. Surprisingly, the degeneracy of the H6 CB (a proposed Weyl node) is lifted and the spin-split VB gap is reduced upon photoexcitation before relaxing to equilibrium as the carriers decay. Using ab initio density functional theory (DFT) calculations, we conclude that the dynamic band structure is caused by a photoinduced shear strain in the Te film that breaks the screw symmetry of the crystal. The band-edge anisotropy is also reflected in the hot carrier decay rate, which is a factor of two slower along the c-axis than perpendicular to it. The majority of photoexcited carriers near the band-edge are seen to recombine within 30 ps while higher lying transitions observed near 1.2 eV appear to have substantially longer lifetimes, potentially due to contributions of intervalley processes in the recombination rate. These new findings shed light on the strong correlation between photoinduced carriers and electronic structure in anisotropic crystals, which opens a potential pathway for designing novel Te-based devices that take advantage of the topological structures as well as strong spin-related properties.

Suggested Citation

  • Giriraj Jnawali & Yuan Xiang & Samuel M. Linser & Iraj Abbasian Shojaei & Ruoxing Wang & Gang Qiu & Chao Lian & Bryan M. Wong & Wenzhuo Wu & Peide D. Ye & Yongsheng Leng & Howard E. Jackson & Leigh M., 2020. "Ultrafast photoinduced band splitting and carrier dynamics in chiral tellurium nanosheets," Nature Communications, Nature, vol. 11(1), pages 1-10, December.
  • Handle: RePEc:nat:natcom:v:11:y:2020:i:1:d:10.1038_s41467-020-17766-5
    DOI: 10.1038/s41467-020-17766-5
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    Cited by:

    1. Mingjin Dai & Chongwu Wang & Bo Qiang & Yuhao Jin & Ming Ye & Fakun Wang & Fangyuan Sun & Xuran Zhang & Yu Luo & Qi Jie Wang, 2023. "Long-wave infrared photothermoelectric detectors with ultrahigh polarization sensitivity," Nature Communications, Nature, vol. 14(1), pages 1-11, December.
    2. Junchao Ma & Bin Cheng & Lin Li & Zipu Fan & Haimen Mu & Jiawei Lai & Xiaoming Song & Dehong Yang & Jinluo Cheng & Zhengfei Wang & Changgan Zeng & Dong Sun, 2022. "Unveiling Weyl-related optical responses in semiconducting tellurium by mid-infrared circular photogalvanic effect," Nature Communications, Nature, vol. 13(1), pages 1-7, December.
    3. Linlin Li & Shufang Zhao & Wenhao Ran & Zhexin Li & Yongxu Yan & Bowen Zhong & Zheng Lou & Lili Wang & Guozhen Shen, 2022. "Dual sensing signal decoupling based on tellurium anisotropy for VR interaction and neuro-reflex system application," Nature Communications, Nature, vol. 13(1), pages 1-12, December.

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