for distribution - thanks

[CM ICTP - Trieste]

									07/05

JOINT ICTP/SISSA CONDENSED MATTER SEMINAR
Academic Year 2006/07



Seminar Room - Main Building  (first floor)



Wednesday, 18 July -     4:00 p.m.



G. GIULIANI   ( Purdue University, West Lafayette )


" New paradigm for spin response in a two-dimensional electron liquid 
with Rashba spin-orbit coupling "


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INFORMAL SEMINAR





Thursday, 19 July   -    11:00 a.m.




Lecture Room 'C' -  Main Bldg. - terrace level



S. BASU  ( Indian Institute of Technology, Guwahati )


"Bound states and phase separation in a t-J model"


Abstract

In this talk I shall present the low density phase diagram for a t - J 
model on two dimensional square and honeycomb lattices.  The phase 
diagram as a function of the exchange interaction, J, in both systems 
possesses three distinct phases, viz. a gas of free electrons, (ii) a 
gas of pairs and finally (iii) a fully phase separated state.  Further, 
it is rigorously proven that the phase boundary for the first phase 
(gas of electrons) remains same in both the lattice geometries 
considered here (more generally it is shown to be true for all 
bipartite lattices and is independent of dimensionality of the system), 
while for the latter phases, the boundaries are somewhat different. 
Moreover, the existence of bigger clusters (bound states of three and 
four electrons etc.) are carefully investigated using exact 
diagonalization (ED) and variational studies and possibility for them 
to occur in the phase diagram is ruled out.  Implications of such 
studies to superconductivity are discussed.