https://doi.org/10.1140/epjb/e2008-00423-3
Extended Hubbard model in the presence of a magnetic field
1
Dipartimento di Fisica “E.R. Caianiello” –
Unità CNISM di Salerno, Università degli Studi di Salerno, Via
S. Allende, 84081 Baronissi (SA), Italy
2
Dipartimento di
Fisica and Sezione I.N.F.N., Università degli Studi di Perugia, Via A. Pascoli, 06123 Perugia, Italy
Corresponding author: a francescopaolo.mancini@pg.infn.it
Received:
14
July
2008
Revised:
13
September
2008
Published online:
22
November
2008
Within the Green's function and equations of motion formalism it is possible to exactly solve a large class of models useful for the study of strongly correlated systems. Here, we present the exact solution of the one-dimensional extended Hubbard model with on-site U and first nearest neighbor repulsive V interactions in the presence of an external magnetic field h, in the narrow band limit. At zero temperature our results establish the existence of four phases in the three-dimensional space (U, n, h) – n is the filling – with relative phase transitions, as well as different types of charge ordering. The magnetic field may dramatically affect the behavior of thermodynamic quantities, inducing, for instance, magnetization plateaus in the magnetization curves, and a change from a single to a double-peak structure in the specific heat. According to the value of the particle density, we find one or two critical fields, marking the beginning of full or partial polarization. A detailed study of several thermodynamic quantities is also presented at finite temperature.
PACS: 71.10.Fd – Lattice fermion models / 75.30.Kz – Magnetic phase boundaries / 71.10.-w – Theories and models of many-electron systems
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2008