| Title |
|
|
|
Quantum cascades in nano-engineered superconductors : geometrical, thermal and paramagnetic effects
| |
| Author |
|
|
|
| |
| Abstract |
|
|
|
| The effect of a parallel magnetic field on the orbital motion of electrons in high-quality superconducting nanowires resulting in a superconductor-to-normal 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 Bogoliubov-de Gennes equations for a hollow nanocylinder, we investigate how the quantum-size cascades depend on the confining geometry, i.e., by changing the cylinder radius R and its thickness d we cover the range from the nanowire-like to the nanofilm-like regime. The cascades are shown to become much less pronounced when increasing R/d, i.e., when the nanofilm-like regime is approached. When the temperature is non-zero they are thermally smoothed. This includes the spin-magnetic-field interaction which reduces the critical (depairing) parallel magnetic field H-c,H-parallel to but does not have any qualitative effect on the quantum cascades. From our calculations it is seen that the paramagnetic limiting field H-par significantly exceeds H-c,H-parallel to even in extremely narrow nanocylinders, i.e., when R, d are down to a few nanometers, and H-c,H-parallel to is only about 10% larger when switching-off the spin-magnetic-field interaction in this case. Both characteristic fields, H-c,H-parallel to and H-par, exhibit pronounced quantum-size oscillations. We demonstrate that the quantum cascades and the quantum-size oscillations survive in the presence of surface roughness. | | |
| Language |
|
|
|
English
| |
| Source (journal) |
|
|
|
Journal of physics : condensed matter. - London | |
| Publication |
|
|
|
London : 2012
| |
| ISSN |
|
|
|
0953-8984
| |
| Volume/pages |
|
|
|
24:26(2012), 17 p.
| |
| Article Reference |
|
|
|
265702
| |
| ISI |
|
|
|
000305640800014
| |
| Medium |
|
|
|
E-only publicatie
| |
| Full text (Publisher's DOI) |
|
|
| | |
| Full text (publisher's version - intranet only) |
|
|
| | |
|