Title 



Quantum cascades in nanoengineered superconductors : geometrical, thermal and paramagnetic effects
 
Author 



 
Abstract 



The effect of a parallel magnetic field on the orbital motion of electrons in highquality superconducting nanowires resulting in a superconductortonormal transition which occurs through a cascade of jumps in the order parameter as a function of the magnetic field. Such cascades originate from the transverse size quantization that splits the conduction band into a series of subbands. Here, based on a numerical solution of the Bogoliubovde Gennes equations for a hollow nanocylinder, we investigate how the quantumsize cascades depend on the confining geometry, i.e., by changing the cylinder radius R and its thickness d we cover the range from the nanowirelike to the nanofilmlike regime. The cascades are shown to become much less pronounced when increasing R/d, i.e., when the nanofilmlike regime is approached. When the temperature is nonzero they are thermally smoothed. This includes the spinmagneticfield interaction which reduces the critical (depairing) parallel magnetic field Hc,Hparallel to but does not have any qualitative effect on the quantum cascades. From our calculations it is seen that the paramagnetic limiting field Hpar significantly exceeds Hc,Hparallel to even in extremely narrow nanocylinders, i.e., when R, d are down to a few nanometers, and Hc,Hparallel to is only about 10% larger when switchingoff the spinmagneticfield interaction in this case. Both characteristic fields, Hc,Hparallel to and Hpar, exhibit pronounced quantumsize oscillations. We demonstrate that the quantum cascades and the quantumsize oscillations survive in the presence of surface roughness.   
Language 



English
 
Source (journal) 



Journal of physics : condensed matter.  London  
Publication 



London : 2012
 
ISSN 



09538984
 
Volume/pages 



24:26(2012), 17 p.
 
Article Reference 



265702
 
ISI 



000305640800014
 
Medium 



Eonly publicatie
 
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