Charge-Order on the Triangular Lattice: A Mean-Field Study for the Lattice S = 1/2 Fermionic Gas

dc.contributor.authorKapcia, Konrad Jerzy
dc.date.accessioned2021-05-04T17:11:49Z
dc.date.available2021-05-04T17:11:49Z
dc.date.issued2021-04-30
dc.description.abstractThe adsorbed atoms exhibit tendency to occupy a triangular lattice formed by periodic potential of the underlying crystal surface. Such a lattice is formed by, e.g., a single layer of graphane or the graphite surfaces as well as (111) surface of face-cubic center crystals. In the present work, an extension of the lattice gas model to S=1/2 fermionic particles on the two-dimensional triangular (hexagonal) lattice is analyzed. In such a model, each lattice site can be occupied not by only one particle, but by two particles, which interact with each other by onsite U and intersite W1 and W2 (nearest and next-nearest-neighbor, respectively) density-density interaction. The investigated hamiltonian has a form of the extended Hubbard model in the atomic limit (i.e., the zero-bandwidth limit). In the analysis of the phase diagrams and thermodynamic properties of this model with repulsive W1>0, the variational approach is used, which treats the onsite interaction term exactly and the intersite interactions within the mean-field approximation. The ground state (T=0) diagram for W2≤0 as well as finite temperature (T>0) phase diagrams for W2=0 are presented. Two different types of charge order within √3×√3 unit cell can occur. At T=0, for W2=0 phase separated states are degenerated with homogeneous phases (but T>0 removes this degeneration), whereas attractive W2<0 stabilizes phase separation at incommensurate fillings. For U/W1<0 and U/W1>1/2 only the phase with two different concentrations occurs (together with two different phase separated states occurring), whereas for small repulsive 0<U/W1<1/2 the other ordered phase also appears (with tree different concentrations in sublattices). The qualitative differences with the model considered on hypercubic lattices are also discussed.pl
dc.description.articlenumber1181pl
dc.description.copybook5pl
dc.description.journaltitleNanomaterialspl
dc.description.sponsorshipNational Science Centre (NCN, Poland) - Grant SONATINA 1 no. UMO-2017/24/C/ST3/00276; scholarship of the Minister of Science and Higher Education (Poland) for outstanding young scientists (2019 edition, no. 821/STYP/14/2019)pl
dc.description.volume11pl
dc.identifier.citationNanomaterials 2021, vol. 11 (5), 1181pl
dc.identifier.doihttps://doi.org/10.3390/nano11051181
dc.identifier.issn2079-4991
dc.identifier.urihttps://hdl.handle.net/10593/26265
dc.language.isoengpl
dc.publisherMDPIpl
dc.rightsUznanie autorstwa 3.0 Polska*
dc.rightsinfo:eu-repo/semantics/openAccesspl
dc.rights.urihttp://creativecommons.org/licenses/by/3.0/pl/*
dc.subjectcharge orderpl
dc.subjecttriangular latticepl
dc.subjectextended Hubbard modelpl
dc.subjectatomic limitpl
dc.subjectmean-field theorypl
dc.subjectphase diagrampl
dc.subjectlonger-range interactionspl
dc.subjectthermodynamic propertiespl
dc.subjectfermionic lattice gaspl
dc.subjectadsorption on the surfacepl
dc.titleCharge-Order on the Triangular Lattice: A Mean-Field Study for the Lattice S = 1/2 Fermionic Gaspl
dc.typeArtykułpl

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