APL Materials (Jul 2024)

Dimensionality-driven power-law gap in the bilayer TaTe2 grown by molecular-beam epitaxy

  • Bruno Kenichi Saika,
  • Satoshi Yoshida,
  • Markel Pardo-Almanza,
  • Natsuki Mitsuishi,
  • Masato Sakano,
  • Yuita Fujisawa,
  • Yue Wang,
  • Yoshihiro Iwasa,
  • Hideki Matsuoka,
  • Hidefumi Takahashi,
  • Shintaro Ishiwata,
  • Yoshinori Okada,
  • Masaki Nakano,
  • Kyoko Ishizaka

DOI
https://doi.org/10.1063/5.0213957
Journal volume & issue
Vol. 12, no. 7
pp. 071105 – 071105-7

Abstract

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Reducing dimensionality can induce profound modifications to the physical properties of a system. In two-dimensional TaS2 and TaSe2, the charge-density wave phase accompanies a Mott transition, thus realizing the strongly correlated insulating state. However, this scenario deviates from TaTe2 due to p–d hybridization, resulting in a substantial contribution of Te 5p at the Fermi level. Here, we show that, differently from the Mott insulating phase of its sister compounds, bilayer TaTe2 hosts a power-law (V-shaped) gap at the Fermi level reminiscent of a Coulomb gap. It suggests the possible role of unscreened long-range Coulomb interactions emerging in lowered dimensions, potentially coupled with a disordered short-range charge-density wave. Our findings reveal the importance of long-range interactions sensitive to interlayer screening, providing another venue for the interplay of complex quantum phenomena in two-dimensional materials.