Supercluster of electrons in ultrathin TaSe2 nanocrystals

• Published in: Journal of the Physical Society of Japan 2006-02, Vol.75 (2)
• Main Authors: TOSHIMA, Takeshi, INAGAKI, Katsuhiko, HATAKENAKA, Noriyuki, TANDA, Satoshi
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic structure of nanoscale materials : clusters, nanoparticles, nanotubes, and nanocrystals; Exact sciences and technology; Nanocrystals; Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; Physics; Structure of solids and liquids; crystallography
• ISSN: 0031-9015; 1347-4073
• DOI: 10.1143/JPSJ.75.024706

We discover a supercluster of electrons in the ultrathin TaSe2 crystals synthesized by our developed de-chalcogenide method. The supercluster has an unexpected structure containing 61 electrons denoted by \\sqrt61×\\sqrt61, in addition to a \\sqrt49×\\sqrt49 supercluster based on \\sqrt7×\\sqrt7 clusters expected in triangle lattices. This new hierarchal structure and successive clustering cannot be explained by a conventional electron clustering mechanism assisted by background lattice distortions, i.e., charge-density-wave formation mechanism based on Fermi surface nesting. We propose an alternative possible formation mechanism based on saddle-point nesting, taking into account a trigonal symmetry as well as lattice distortion energy.