Mott insulating states and quantum phase transitions of correlated SU(2N) Dirac fermions

Zhichao Zhou, Da Wang, Zi Yang Meng, Yu Wang, and Congjun Wu
Phys. Rev. B 93, 245157 – Published 29 June 2016

Abstract

The interplay between charge and spin degrees of freedom in strongly correlated fermionic systems, in particular of Dirac fermions, is a long-standing problem in condensed matter physics. We investigate the competing orders in the half-filled SU(2N) Hubbard model on a honeycomb lattice, which can be accurately realized in optical lattices with ultracold large-spin alkaline-earth fermions. Employing large-scale projector determinant quantum Monte Carlo simulations, we have explored quantum phase transitions from the gapless Dirac semimetals to the gapped Mott insulating phases in the SU(4) and SU(6) cases. Both of these Mott insulating states are found to be columnar valence bond solid (cVBS) and to be absent of the antiferromagnetic Néel ordering and the loop current ordering. Inside the cVBS phases, the dimer ordering is enhanced by increasing fermion components and behaves nonmonotonically as the interaction strength increases. Although the transitions generally should be of first order due to a cubic invariance possessed by the cVBS order, the coupling to gapless Dirac fermions can soften the transitions to second order through a nonanalytic term in the free energy. Our simulations provide important guidance for the experimental explorations of novel states of matter with ultracold alkaline-earth fermions.

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  • Received 18 February 2016
  • Revised 25 May 2016

DOI:https://doi.org/10.1103/PhysRevB.93.245157

©2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Zhichao Zhou1, Da Wang2, Zi Yang Meng3, Yu Wang1,*, and Congjun Wu4,†

  • 1School of Physics and Technology, Wuhan University, Wuhan 430072, China
  • 2National Laboratory of Solid State Microstructures and School of Physics, Nanjing University, Nanjing, 210093, China
  • 3Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
  • 4Department of Physics, University of California, San Diego, California 92093, USA

  • *yu.wang@whu.edu.cn
  • wucj@physics.ucsd.edu

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Issue

Vol. 93, Iss. 24 — 15 June 2016

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