Anisotropic scattering rates and antiferromagnetic precursor effects in the t-t'-U Hubbard model

2000 ◽  
Vol 18 (3) ◽  
pp. 429-433 ◽  
Author(s):  
J. Altmann ◽  
W. Brenig ◽  
A.P. Kampf
Keyword(s):  
Hubbard Model ◽  
Anisotropic Scattering ◽  
Precursor Effects ◽  
Scattering Rates

THEORY OF CRITICAL CHARGE FLUCTUATIONS AND PSEUDOGAP FORMATION IN THE SINGLE-BAND HUBBARD MODEL

2000 ◽  
Vol 14 (25n27) ◽  
pp. 3000-3005 ◽  
Author(s):  
ROBERTA CITRO ◽  
MARIO MARINARO
Keyword(s):  
Hubbard Model ◽  
Density Wave ◽  
Charge Ordering ◽  
Single Band ◽  
Electron Interaction ◽  
Charge Fluctuations ◽  
Effective Electron ◽  
Critical Charge ◽  
A Charge ◽  
Precursor Effects

Within a single-band Hubbard model, treated by means of a strong-coupling approach based on a cumulant expansion, we investigate the existence of critical charge fluctuations (CCF) that could give rise to a phase separation (PS) or a charge density wave, by means of a Bethe-Salpeter equation for the vertex function in the particle-hole channel. We discuss the relevance of the precursor effects of charge ordering on the self-energy of the electrons and the non-Fermi liquid behavior arising from an effective electron-electron interaction.

Scattering Rings in Birefringent Porous Silicon

2003 ◽  
Vol 762 ◽  
Author(s):  
Claudio J. Oton ◽  
Zeno Gaburro ◽  
Mher Ghulinyan ◽  
Nicola Daldosso ◽  
Lucio Pancheri ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Light Scattering ◽  
Porous Silicon ◽  
Direct Measurement ◽  
Optical Anisotropy ◽  
Oblique Incidence ◽  
Laser Light ◽  
Anisotropic Scattering ◽  
Scattering Measurements

AbstractWe report the observation of strongly anisotropic scattering of laser light at oblique incidence on (100)-oriented porous silicon layers. We performed angle-resolved light scattering measurements and three concentric rings were observed. Modeling porous silicon by means of nanometric columnar air pores and an effective anisotropic uniaxial dielectric constant explains the observed phenomenon, and besides, the observation of the angle aperture of these rings allows a direct measurement of relative birefringence. We finally study the changes of optical anisotropy after different modifications of the structure.

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