| Autor: |
HESLINGA, DR, KLAPWIJK, TM |
| Jazyk: |
angličtina |
| Rok vydání: |
1993 |
| Předmět: |
|
| Zdroj: |
Physical Review. B: Condensed Matter and Materials Physics, 47(9), 5157-5164. AMER PHYSICAL SOC |
| ISSN: |
0163-1829 |
| Popis: |
Motivated by the observation of a superconducting energy gap far above the equilibrium critical temperature T(c) in an Al film forming the center electrode of a Nb/AlO(x)/Al/AlO(x)/Nb structure we analyze the mechanism of gap enhancement in symmetric double-barrier superconducting tunnel junctions. It is found that such structures are very effective in creating a nonthermal distribution of quasiparticles in the middle electrode. At certain bias conditions this leads, according to the BCS gap equation, to the appearance of a nonzero superconducting energy gap even at temperatures up to several times the equilibrium T(c). So the double-barrier arrangement offers the remarkable possibility of making a material become superconducting by applying a voltage or passing a current. Calculated current-voltage characteristics exhibit current steps at voltages eV=2(DELTA(Nb)-DELTA(Al)) and eV=2(DELTA(Nb)+DELTA(Al)) in agreement with measured curves. Calculations of the thermodynamic stability of the nonequilibrium superconducting state indicate the possibility of hysteresis effects around these current steps. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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