Dynamical resilience to disorder: The dilute Hubbard model on the Lieb lattice

Journal Article · Thu Apr 09 00:00:00 EDT 2020 · Physical Review. B

DOI:https://doi.org/10.1103/physrevb.101.165109· OSTI ID:1802699

Oliveira-Lima, L. ^[1]; Costa, N. C. ^[2]; de Lima, J. Pimentel ^[3]; Scalettar, R. T. ^[4]; R. dos Santos, R. ^[5]

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1. Universidade Federal do Piauí (Brazil); OSTI
2. Universidade Federal do Rio de Janeiro (Brazil); International School for Advanced Studies (SISSA), Trieste (Italy)
3. Universidade Federal do Piauí (Brazil)
4. Univ. of California, Davis, CA (United States)
5. Universidade Federal do Rio de Janeiro (Brazil)

In itinerant systems, electron-electron interactions may lead to the formation of local magnetic moments and their effective exchange coupling, which in turn gives rise to long-range magnetic order. Therefore, when moment formation is weakened, such as in the single-band Hubbard model on a square lattice with the on-site repulsion being randomly switched off on a fraction $$\textit{x}$$ of sites, magnetic order is suppressed beyond some critical $$x_c$$, which was found to lie below the classical percolation threshold $$x^{\text{(perc,sq)}}_c$$. Here we study dilute magnetism in flat band systems, namely, in the Hubbard model on a “Lieb” lattice. Interestingly, we show that magnetic order persists to x almost twice as large as the classical percolation threshold for the lattice, thus emphasizing the central role of electron itinerancy to the magnetic response. Further, the analysis of the orbital-resolved order parameters reveals that the contribution of the fourfold coordinated $$\textit{“d”}$$ sites to magnetism is dramatically affected by dilution, while the localized $$\textit{“p”}$$ states of the flat band provide the dominant contribution to long-range correlations. We also examine the transport properties, which suggest the existence of an insulator-to-metal transition in the same range of the critical magnetic dilution.

• Research Organization: Univ. of California, Davis, CA (United States)
• Sponsoring Organization: Brazilian National Council for Scientific and Technological Development (CNPq); Coordination for the Improvement of Higher Education Personnel (CAPES); Fundação de Amparo à Pesquisa do Estado do Piauí (FAPEPI); Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ); USDOE; USDOE Office of Science (SC)
• Grant/Contract Number: SC0014671
• OSTI ID: 1802699
• Alternate ID(s): OSTI ID: 1632943
• Journal Information: Physical Review. B, Journal Name: Physical Review. B Journal Issue: 16 Vol. 101; ISSN 2469-9950
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
Materials Science
Physics