Thursday's seminar

[CM ICTP - Trieste]

Seminar on  Disorder and strong electron correlations





Thursday, 11 December      -  11:00 a.m.





Seminar Room,  Leonardo Building - first floor



A. SAHA   ( Harish-Chandra Research Institute, Allahabad )



" Transport through superconducting junction of multiple one- 
dimensional quantum wires "



Abstract



We investigate transport properties of a superconducting junction of  
one-dimensional quantum wires. We include the effect of electron- 
electron interaction within the one-dimensional quantum wires using a  
weak interaction renormalization group (WIRG) procedure. Due to the  
proximity effect, transport across the junction occurs via direct  
tunneling as well as via crossed Andreev channel. We find that the  
fixed point structure of this system is far more rich than the fixed  
point structure of a normal metal-superconductor (NS) junction, where  
we only have two fixed points - the fully insulating fixed point or  
the Andreev fixed point. Even a two wire system with a  
superconducting junction i.e. a normal metal-superconductor-normal  
metal (NSN) structure, has non-trivial fixed points with intermediate  
transmissions and reflections. We demonstrate possible scenarios for  
production of pure spin current through such junctions and show that  
there are fixed points in the theory which correspond to the case of  
pure spin current. We have also shown that (a) effects due to  
inclusion of electron-electron interaction induced back-scattering in  
the wire, and (b) competition between the charge transport via the  
electron and hole channels across the junction give rise to a non- 
monotonic behavior of subgap conductance as a function of temperature.