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  ^[1]; Scalettar, R. T. ^[3]; R. dos Santos, R.  ^[4]

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1. Universidade Federal do Piauí (Brazil)
2. Universidade Federal do Rio de Janeiro (Brazil); International School for Advanced Studies (SISSA), Trieste (Italy)
3. Univ. of California, Davis, CA (United States)
4. 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: USDOE Office of Science (SC); Coordination for the Improvement of Higher Education Personnel (CAPES); Brazilian National Council for Scientific and Technological Development (CNPq); Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ); Fundação de Amparo à Pesquisa do Estado do Piauí (FAPEPI)
• Grant/Contract Number: SC0014671
• OSTI ID: 1802699
• Alternate ID(s): OSTI ID: 1632943
• Journal Information: Physical Review. B, Vol. 101, Issue 16; 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