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Title: Enhanced correlations and superconductivity in weakly interacting partially flat-band systems: A determinantal quantum Monte Carlo study

Abstract

Motivated by recent experiments realizing correlated phenomena and superconductivity in two-dimensional (2D) van der Waals devices, we consider the general problem of whether correlation effects may be enhanced by modifying band structure while keeping a fixed weak interaction strength. Using determinantal quantum Monte Carlo, we study the 2D Hubbard model for two different band structures: a regular nearest-neighbor tight-binding model and a partially flat-band structure containing a nondispersing region, with identical total noninteracting bandwidth W tot. For both repulsive and attractive weak interactions (|U| $$\ll$$ W$$_{tot}$$, correlated phenomena are significantly stronger in the partially flat model. In the repulsive case, even with $U$ being an order of magnitude smaller than W$$_{tot}$$, we find the presence of a Mott insulating state near half filling of the flat region in momentum space. In the attractive case, where generically the ground state is superconducting, the partially flat model exhibits significantly enhanced superconducting transition temperatures. These results suggest the possibility of engineering correlation effects in materials by tuning the noninteracting electronic dispersion.

Authors:
 [1];  [2];  [3];  [4]
  1. Stanford Univ., CA (United States). Dept. of Physics; SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Institute for Materials and Energy Science (SIMES)
  2. Pasargad Inst. for Advanced Innovative Solutions, Tehran (Iran); Washington Univ., St. Louis, MO (United States). Dept. of Physics
  3. Washington Univ., St. Louis, MO (United States). Dept. of Physics
  4. Stanford Univ., CA (United States). Dept. of Physics; Stanford Univ., CA (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
OSTI Identifier:
1546747
Alternate Identifier(s):
OSTI ID: 1546233
Grant/Contract Number:  
AC02-76SF00515; NSF 1411229
Resource Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 99; Journal Issue: 23; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Citation Formats

Huang, Edwin W., Vaezi, Mohammad-Sadegh, Nussinov, Zohar, and Vaezi, Abolhassan. Enhanced correlations and superconductivity in weakly interacting partially flat-band systems: A determinantal quantum Monte Carlo study. United States: N. p., 2019. Web. doi:10.1103/physrevb.99.235128.
Huang, Edwin W., Vaezi, Mohammad-Sadegh, Nussinov, Zohar, & Vaezi, Abolhassan. Enhanced correlations and superconductivity in weakly interacting partially flat-band systems: A determinantal quantum Monte Carlo study. United States. doi:10.1103/physrevb.99.235128.
Huang, Edwin W., Vaezi, Mohammad-Sadegh, Nussinov, Zohar, and Vaezi, Abolhassan. Thu . "Enhanced correlations and superconductivity in weakly interacting partially flat-band systems: A determinantal quantum Monte Carlo study". United States. doi:10.1103/physrevb.99.235128.
@article{osti_1546747,
title = {Enhanced correlations and superconductivity in weakly interacting partially flat-band systems: A determinantal quantum Monte Carlo study},
author = {Huang, Edwin W. and Vaezi, Mohammad-Sadegh and Nussinov, Zohar and Vaezi, Abolhassan},
abstractNote = {Motivated by recent experiments realizing correlated phenomena and superconductivity in two-dimensional (2D) van der Waals devices, we consider the general problem of whether correlation effects may be enhanced by modifying band structure while keeping a fixed weak interaction strength. Using determinantal quantum Monte Carlo, we study the 2D Hubbard model for two different band structures: a regular nearest-neighbor tight-binding model and a partially flat-band structure containing a nondispersing region, with identical total noninteracting bandwidth Wtot. For both repulsive and attractive weak interactions (|U| $\ll$ W$_{tot}$, correlated phenomena are significantly stronger in the partially flat model. In the repulsive case, even with $U$ being an order of magnitude smaller than W$_{tot}$, we find the presence of a Mott insulating state near half filling of the flat region in momentum space. In the attractive case, where generically the ground state is superconducting, the partially flat model exhibits significantly enhanced superconducting transition temperatures. These results suggest the possibility of engineering correlation effects in materials by tuning the noninteracting electronic dispersion.},
doi = {10.1103/physrevb.99.235128},
journal = {Physical Review B},
number = 23,
volume = 99,
place = {United States},
year = {2019},
month = {6}
}

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