A neck-collapsing-type lifshitz transition induced by orbital symmetry breaking in lightly hole doped t 2g bands

Kazumichi Ikedo, Yuki Wakisaka, Sizuka Hirata, Kou Takubo, Takashi Mizokawa

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We report on a new type of orbital symmetry breaking in the CoO 2 triangular lattice with hole doped t 2g bands. Unrestricted Hartree-Fock calculations on a multi-orbital d-p Hamiltonian show that, in the lightly hole doped t 2g bands, the é g orbitals are fully occupied with a circular charge distribution, and the doped holes in the a 1g band form a hole pocket sandwiched by two concentric Fermi surfaces with sixfold (and almost continuous) rotational symmetry. This symmetric state has an instability to an anisotropic state with twofold rotational symmetry, where the hole pocket is split into two pieces. This transition is governed by the anisotropic interaction between the a 1g and é g orbitals.

Original languageEnglish
Article number063707
JournalJournal of the Physical Society of Japan
Issue number6
Publication statusPublished - 2009 Jun
Externally publishedYes



  • Band jahn-teller effect
  • CoO triangular lattice
  • Lifshitz transition
  • Orbital degeneracy

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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