University
of Toronto
Physics Department
Quantum Optics and Condensed Matter
MONDAY SEMINAR
University
of Toronto
| Speaker: | DR. MONA BERCIU
Department of Physics University of Toronto |
|
| Topic : | D-WAVE CHARGE CARRIER PAIRING IN A PURELY REPULSIVE 2D ELECTRON SYSTEM | |
| Time : | Monday, November 15, 1999 at 12:10 p.m. | |
| Place : | Room 408, Burton Tower 60 St. George Street / 255 Huron Street |
Abstract
In this talk, we present a new microscopic model for a strongly
repulsive electron gas on a 2D square lattice. We suggest that nearest
neighbor Coulomb Repulsion stabilizes a state in which electrons undergo
a ``somersault'' in their internal spin-space (spin-flux). When this spin-1/2
antiferromagnetic (AFM) insulator is doped, the charge carriers nucleate
mobile, charged, bosonic vortex solitons accompanied by unoccupied states
deep inside the Mott-Hubbard charge-transfer gap. This model provides a
unified microscopic basis for (i) non-Fermi-liquid transport properties,
(ii) mid-infrared optical absorption, (iii) destruction of AFM long range
order with doping, (iv) angled resolved spectroscopy (ARPES), and (v) d-wave
preformed charged carrier pairs. The approximation used to study the 2D
spin-flux Hubbard model is the Configuration Interaction Method.
In 1D, this approximation leads to excellent agreement with the exact Bethe
Ansatz results, as well as a clear demonstration of the spin-charge separation:
the charge is carried by charged bosonic domain-walls, while the spin is
carried by neutral fermionic domain-walls.
Local Host: Prof. Sajeev
John 
(416-978-3459)