scholarly journals Ferromagnetism in d-Dimensional SU(n) Hubbard Models with Nearly Flat Bands

2021 ◽  
Vol 182 (1) ◽  
Author(s):  
Kensuke Tamura ◽  
Hosho Katsura
Keyword(s):  
Single Particle ◽  
Ground States ◽  
Coulomb Repulsion ◽  
Particle Spectrum ◽  
Finite Range ◽  
Rigorous Results ◽  
Hubbard Models ◽  
Flat Bands ◽  
Unit Cells ◽  
Number Of Particles

AbstractWe present rigorous results for the SU(n) Fermi–Hubbard models with finite-range hopping in d ($$\ge 2$$ ≥ 2 ) dimensions. The models are defined on a class of decorated lattices. We first study the models with flat bands at the bottom of the single-particle spectrum and prove that the ground states exhibit SU(n) ferromagnetism when the number of particles is equal to the number of unit cells. We then perturb the models by adding particular hopping terms and make the bottom bands dispersive. Under the same filling condition, it is proved that the ground states remain SU(n) ferromagnetic when the bottom bands are sufficiently flat and the Coulomb repulsion is sufficiently large.

scholarly journals Rigorous results on superconducting ground states for attractive extended Hubbard models

1996 ◽  
Vol 53 (9) ◽  
pp. 5153-5156 ◽  
Author(s):  
Arianna Montorsi ◽  
David K. Campbell
Keyword(s):  
Ground States ◽  
Rigorous Results ◽  
Hubbard Models

The Influence of Multiple Inclusions on the Cauchy Stress of a Spherical Particle-Reinforced Composite Under Uniaxial Loading

2014 ◽  
Author(s):  
Ke Niu ◽  
Armin Abedini ◽  
Zengtao Chen
Keyword(s):  
Spherical Particle ◽  
Single Particle ◽  
Volume Fraction ◽  
Unit Cell ◽  
Spherical Particles ◽  
Uniaxial Tensile ◽  
Cauchy Stress ◽  
Particle Volume ◽  
Volume Fractions ◽  
Unit Cells

This paper investigates the influence of multiple inclusions on the Cauchy stress of a spherical particle-reinforced metal matrix composite (MMC) under uniaxial tensile loading condition. The approach of three-dimensional cubic multi-particle unit cell is used to investigate the 15 non-overlapping identical spherical particles which are randomly distributed in the unit cell. The coordinates of the center of each particle are calculated by using the Random Sequential Adsorption algorithm (RSA) to ensure its periodicity. The models with reinforcement volume fractions of 10%, 15%, 20% and 25% are evaluated by using the finite element method. The behaviour of Cauchy stress for each model is analyzed at a far-field strain of 5%. For each reinforcement volume fraction, four models with different particle spatial distributions are evaluated and averaged to achieve a more accurate result. At the same time, single-particle unit cell and analytical model were developed. The stress-strain curves of multi-particle unit cells are compared with single-particle unit cells and the tangent homogenization model coupled with the Mori-Tanaka method. Only little scatters were found between unit cells with the same particle volume fractions. Multi-particle unit cells predict higher response than single particle unit cells. As the volume fraction of reinforcements increases, the Cauchy stress of MMCs increases.

scholarly journals Ferromagnetism in multiband Hubbard models: From weak to strong Coulomb repulsion

1996 ◽  
Vol 54 (6) ◽  
pp. 4056-4067 ◽  
Author(s):  
Karlo Penc ◽  
Hiroyuki Shiba ◽  
Frédéric Mila ◽  
Takuya Tsukagoshi
Keyword(s):  
Coulomb Repulsion ◽  
Hubbard Models ◽  
Strong Coulomb

EXACT WAVEFUNCTION OF THE ONE-DIMENSIONAL DOUBLE-EXCHANGE MODEL WITH ONE ELECTRON

2012 ◽  
Vol 26 (30) ◽  
pp. 1250154 ◽  
Author(s):  
KYOHEI NAKANO ◽  
ROBERT EDER ◽  
YUKINORI OHTA
Keyword(s):  
Single Particle ◽  
Double Exchange ◽  
Exchange Interactions ◽  
Exchange Model ◽  
Particle Spectrum ◽  
Lower Edge ◽  
One Dimensional ◽  
Mobile Electron ◽  
Spin Excitations ◽  
The One

We study the one-dimensional double-exchange model with L localized spins and one mobile electron. We solve the Schrödinger equation analytically and obtain the energies and wavefunctions for all the eigenstates with spin S = (l-1)/2 exactly. As an application, we compute the single-particle Green's function. We show that, for vanishing exchange interactions between localized spins, the single-particle spectrum is entirely incoherent and the lowest band has an infinite band mass, i.e., the single electron is localized due to its interaction with the spin excitations. For nonvanishing exchange interactions between localized spins, the lower edge of the spectrum acquires a dispersion but the spectrum remains incoherent with no well-defined quasiparticle peak.

Single particle spectrum of (TMTF)/sub 2/ClO/sub 4/ in the field induced spin density-wave state

1994 ◽  
Author(s):  
J. Lefebvre ◽  
J. Beerens ◽  
C. Bourbonnais ◽  
L.O. Caron ◽  
C. Lenoir ◽  
...  
Keyword(s):  
Spin Density ◽  
Single Particle ◽  
Density Wave ◽  
Spin Density Wave ◽  
Particle Spectrum ◽  
Wave State ◽  
Single Particle Spectrum
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