Instability of the Nagaoka ferromagnetic state of theU=∞Hubbard model

1990 ◽  
Vol 41 (4) ◽  
pp. 2375-2379 ◽  
Author(s):  
B. S. Shastry ◽  
H. R. Krishnamurthy ◽  
P. W. Anderson
Keyword(s):  
Hubbard Model ◽  
Ferromagnetic State

scholarly journals Scaling properties of the ferromagnetic state in the Hubbard model

1994 ◽  
Vol 50 (17) ◽  
pp. 12991-12994 ◽  
Author(s):  
K. Kusakabe ◽  
H. Aoki
Keyword(s):  
Hubbard Model ◽  
Ferromagnetic State ◽  
Scaling Properties

Hubbard model in the ferromagnetic state. Dimer and trimer approach

2005 ◽  
Vol 242 (2) ◽  
pp. 337-341 ◽  
Author(s):  
M. Matlak ◽  
T. Słomska ◽  
B. Grabiec
Keyword(s):  
Hubbard Model ◽  
Ferromagnetic State

On the Ground State of Hubbard Model with Strong Repulsion

1998 ◽  
Vol 12 (29n31) ◽  
pp. 3119-3122
Author(s):  
Ju. V. Mikhailova
Keyword(s):  
Hubbard Model ◽  
Ground State ◽  
Exact Result ◽  
Ferromagnetic State ◽  
Total Spin ◽  
Repulsion Energy ◽  
Strong Repulsion ◽  
Hole Number ◽  
Infinite Repulsion

For square (cubic) Hubbard lattice with infinite repulsion energy U exact result has been obtained: the ferromagnetic state with maximum total spin is not the ground state of system, if the hole number is equal to two.

SINGLE SPIN FLIP IN THE INFINITE U HUBBARD MODEL: HUBBARD OPERATORS, THREE-BODY FADEEV EQUATIONS AND GUTZWILLER WAVE FUNCTIONS

1989 ◽  
Vol 03 (12) ◽  
pp. 1809-1832 ◽  
Author(s):  
Andrei E. Ruckenstein ◽  
Stefan Schmitt-Rink
Keyword(s):  
Hubbard Model ◽  
Mean Field Theory ◽  
Mean Field ◽  
Ferromagnetic State ◽  
Physical Content ◽  
Single Spin ◽  
Hartree Fock ◽  
Spin Flip ◽  
Three Body ◽  
Hubbard Operators

We investigate a recently proposed many-body theory for composite (Hubbard) operators (A.E. Ruckenstein and S. Schmitt-Rink, Phys. Rev. B38, 7188 (1988)) in the context of the problem of a single spin flip in the saturated ferromagnetic state of the infinite U Hubbard model. We prove that the suitably defined strong coupling Hartree-Fock mean field theory leads to results identical to those obtained from the Gutzwiller wave function through exact evaluation of the kinetic energy. Most interestingly, we also show how exactly the same results can be obtained starting from the weak coupling limit by solving analytically the three-body t-matrix (Fadeev) equations in the infinite U limit. This work also sheds light on the physical content of slave boson approximations to which our approach was previously shown to be equivalent in the limit of large spin or orbital degeneracy. For the single spin flip problem we compare our results with those obtained by Bethe-Goldstone perturbation theory, Bethe Ansatz in one dimension, and exact diagonalization studies.

Ferromagnetism in the two-dimensional Hubbard model with long-range hopping

Open Physics ◽  
2013 ◽  
Vol 11 (1) ◽  
Author(s):  
Pavol Farkašovský ◽  
Hana Čenčariková
Keyword(s):  
Hubbard Model ◽  
Long Range ◽  
Quantum Monte Carlo ◽  
Ferromagnetic State ◽  
Critical Value ◽  
Exact Diagonalization ◽  
Two Dimensional ◽  
Wide Range ◽  
Quantum Monte Carlo Method ◽  
Generalized Type

AbstractThe combination of small-cluster exact-diagonalization calculations and the quantum Monte Carlo method is used to examine ferromagnetism in the two-dimensional Hubbard model with a generalized type of hopping. It is found that the long-range hopping with exponentially decaying hopping amplitudes t ij ∼ − q Ri−Rj stabilizes the ferromagnetic state for a wide range of electron interactions U and electron concentrations n > 1. The critical value of the hopping parameter q c above which the ferromagnetic state becomes stable is calculated numerically and the ground-state phase diagram of the model is discussed for physically the most interesting cases.

Stability of the saturated ferromagnetic state in the one-band Hubbard model

1990 ◽  
Vol 41 (16) ◽  
pp. 11697-11700 ◽  
Author(s):  
A. Barbieri ◽  
J. A. Riera ◽  
A. P. Young
Keyword(s):  
Hubbard Model ◽  
Ferromagnetic State ◽  
The One

scholarly journals The Influence of Long-Range Hopping on Ferromagnetism in the Hubbard Model

1998 ◽  
Vol 12 (07n08) ◽  
pp. 803-808 ◽  
Author(s):  
Pavol Farkašovský
Keyword(s):  
Magnetic Field ◽  
Phase Diagram ◽  
External Magnetic Field ◽  
Hubbard Model ◽  
Long Range ◽  
General Expression ◽  
Ferromagnetic State ◽  
Critical Value ◽  
Exact Diagonalization ◽  
Matrix Elements

The phase diagram of the Hubbard model in an external magnetic field is examined by extrapolation of small-cluster exact-diagonalization calculations. Using a general expression for the hopping matrix elements (tij ~ q|i-j|) the influence of long-range hopping (band asymmetry) on ferromagnetism in this model is studied. It is found that the long-range hopping (nonzero q) stabilizes ferromagnetism in an external magnetic field for n > 1. In the opposite limit n≤1 the fully polarized ferromagnetic state is generally suppressed with increasing q. The critical value of magnetic field h below which the ferromagnetic state becomes unstable is calculated numerically.

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