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<p>Stacking of strongly-correlated 2D materials is opening the possibility to demonstrate novel electronic or magnetic ordering phenomena. In this regard the intrinsic polytypism of tantalum dichalcogenides has emerged as a platform to generate clean and controllable material interfaces. Here, we report on the Fermi surface of 4<i>Hb</i>-TaSe<sub>2</sub>, a polytype which consists of alternately stacked layers with octahedral (<i>T</i>) and trigonal prismatic (<i>H</i>) coordination of tantalum in the Se-Ta-Se layers. The material is known to host a charge density wave (CDW) phase with star clusters in the <i>T</i>-layers, intercalated by metallic <i>H</i>-layers, but its momentum resolved electronic structure remains undetermined. Using selective area angle resolved photoemission spectroscopy on the <i>T</i> termination combined with ab initio calculations, we unveil a finely structured Fermi surface arising from band folding in the reconstructed Brillouin zone caused by the CDW star clusters. The star-shaped Fermi surface is rotated away from the high-symmetry directions of the normal phase, and exhibits pseudochirality. Theoretical analysis supports the metallic nature of the system and interlayer interactions leading to hybridization. The work provides a detailed overview on the impact of band hybridization with the CDW on the Fermi surface of a material for new phases of quantum matter.</p>

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Folded pseudochiral Fermi surface in 4Hb-TaSe2 from band hybridization with a charge density wave

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年2月3日

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  • Matthew D. Watson,
  • Andrea Tonelli,
  • Mugerabe Zerabza,
  • Sam Hayward,
  • Rebecca Wilkinson,
  • Ettore Carpene,
  • Cephise Cacho,
  • Valentina De Renzi,
  • Simon Crampin,
  • Enrico Da Como

摘要

Stacking of strongly-correlated 2D materials is opening the possibility to demonstrate novel electronic or magnetic ordering phenomena. In this regard the intrinsic polytypism of tantalum dichalcogenides has emerged as a platform to generate clean and controllable material interfaces. Here, we report on the Fermi surface of 4Hb-TaSe2, a polytype which consists of alternately stacked layers with octahedral (T) and trigonal prismatic (H) coordination of tantalum in the Se-Ta-Se layers. The material is known to host a charge density wave (CDW) phase with star clusters in the T-layers, intercalated by metallic H-layers, but its momentum resolved electronic structure remains undetermined. Using selective area angle resolved photoemission spectroscopy on the T termination combined with ab initio calculations, we unveil a finely structured Fermi surface arising from band folding in the reconstructed Brillouin zone caused by the CDW star clusters. The star-shaped Fermi surface is rotated away from the high-symmetry directions of the normal phase, and exhibits pseudochirality. Theoretical analysis supports the metallic nature of the system and interlayer interactions leading to hybridization. The work provides a detailed overview on the impact of band hybridization with the CDW on the Fermi surface of a material for new phases of quantum matter.