Upcoming seminar by Dr. Alejandro Cabo

[Quantitative Life Sciences]

WEDNESDAY 19 AUGUST,  3:30pm
Budinich Lecture Hall, ICTP Leonardo Building


Alejandro Cabo (former ICTP Senior Associate,Instituto de Cibernetica, Matematica y Fisica - ICIMAF, La Habana, Cuba)
  
"How the insulator and pseudo gap states coalesce beneath the superconductor Dome"
  

Abstract:

The pseudo gap effects and the expected quantum phase transitions (QPT) in
cuprate materials are yet unclear in nature. A single band model of
interacting Tight-Binding (TB) electrons  for the CuO2 planes of these
materials had predicted the existence of definite pseudogap states at
half-filling, after considering that a crystal symmetry breaking and
non-collinear spin orientations of the Hartree-Fock  single particle
states are allowed. After including hole doping in the model, a QPT which
lies beneath the superconducting Dome, is also obtained and is a second
order one. Under its occurrence, an insulator ground state (AFI), showing
strong spin fluctuations at low doping, coalesce with an excited
paramagnetic pseudogap (PPG) state exhibiting a broken lattice symmetry,
at near a critical hole density xc = 0.2. Above this value the system
becomes a paramagnetic metal. The band structures and Fermi surface with
doping are evaluated and their evolution qualitatively resemble the
experimental observations. The analysis suggests a way for searching an ab
initio band calculation scheme being able to derive the Mott properties of
the cuprates without phenomenological inputs.

-- 
Erica Sarnataro
Group Secretary
Quantitative Life Sciences
The Abdus Salam International Centre for Theoretical Physics (ICTP)
Trieste,  Italy
Tel. +39-040-2240623
e-mail: qls at ictp.it