SOME PHONON EFFECTS IN SUPERCONDUCTING TUNNEL JUNCTIONS

1965 ◽  
Vol 43 (4) ◽  
pp. 557-562 ◽  
Author(s):  
J. G. Adler ◽  
J. S. Rogers ◽  
S. B. Woods
Keyword(s):  
Temperature Dependence ◽  
Phonon Spectrum ◽  
Energy Gap ◽  
Tunnel Junctions ◽  
Phonon Energy ◽  
Superconducting Tunnel Junctions ◽  
Tunnel Current ◽  
Broad Group ◽  
Superconducting Energy Gap ◽  
Phonon Structure

Tunneling measurements have been made on junctions consisting of aluminium separated from a second metal by aluminium oxide insulating layers. When the second metal was lead, tin, or indium, the effect of its phonon spectrum on the tunnel current was observed. Results with indium indicate that there is a broad group of phonons at an energy of 5 millivolts and another group at an energy of 13 millivolts in the indium phonon spectrum. The end point of the spectrum is at 14.8 ± 0.1 millivolts. Evidence is presented for a relationship between the strength of the phonon structure, the phonon energy, and the width of the superconducting energy gap from measurements on lead, tin, and indium. Measurements of the temperature dependence of the phonon structure in lead and indium are also reported.

Temperature dependence of the YBa2Cu3O7 energy gap in differently oriented tunnel junctions

2001 ◽  
Vol 24 (3) ◽  
pp. 305-308 ◽  
Author(s):  
F. Giubileo ◽  
A. Jossa ◽  
F. Bobba ◽  
A.I. Akimenko ◽  
A.M. Cucolo
Keyword(s):  
Temperature Dependence ◽  
Energy Gap ◽  
Tunnel Junctions

A Tunneling Study of Superconducting YBa2 Cu3Oy By Contact Junctions At 77 K

1987 ◽  
Vol 99 ◽  
Author(s):  
H. Enomoto ◽  
K. Gotoh ◽  
K. Iida ◽  
Y. Takano ◽  
N. Mori ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Electronic Structures ◽  
Energy Gap ◽  
High Tc ◽  
Bcs Model ◽  
High Tc Superconductor ◽  
Derivative Analysis ◽  
Superconducting Energy Gap

ABSTRACTGiaever tunneling measurements have been applied to investigate the electronic structures of the high Tc superconductor YB2Cu3Oy near Tc. The superconducting energy gap of 17 meV was observed in V-dl/dv curve at 77 K. In the light of BCS model, 2Δ0Δ/kBTc was estimated as 3.3. Several dip structures were observed in the bias region up to 0.5 eV in V-dl/dV curve, using the 3rd derivative analysis. Through the temperature dependence, these structures were found to be associated with the superconductivity.

Local detection of superconducting energy gap by small tunnel junctions

1999 ◽  
pp. 229-232
Author(s):  
A. Kanda ◽  
M.C. Geisler ◽  
K. Ishibashi ◽  
Y. Aoyagi ◽  
T. Sugano
Keyword(s):  
Energy Gap ◽  
Tunnel Junctions ◽  
Superconducting Energy Gap ◽  
Local Detection

Lateral proximity effect and long-range energy-gap gradients in Ta/Al and Nb/Al superconducting tunnel junctions

2001 ◽  
Vol 63 (21) ◽  
Author(s):  
Roland den Hartog ◽  
A. Golubov ◽  
P. Verhoeve ◽  
A. Poelaert ◽  
D. Martin ◽  
...  
Keyword(s):  
Long Range ◽  
Proximity Effect ◽  
Energy Gap ◽  
Tunnel Junctions ◽  
Superconducting Tunnel Junctions

Temperature dependence of the energy gap in superconducting Al–Al2O3–Al tunnel junctions

1968 ◽  
Vol 46 (2) ◽  
pp. 141-145 ◽  
Author(s):  
B. L. Blackford ◽  
R. H. March
Keyword(s):  
Temperature Dependence ◽  
Energy Gap ◽  
Tunnel Junctions ◽  
Small Deviation ◽  
Mean Value ◽  
Bcs Theory ◽  
Energy Gaps ◽  
The Mean ◽  
Gap Values

The most detailed measurements of the energy gap in Al by the tunneling technique have been made using Al–Al2O3-Pb junctions. Determination of the energy gaps from the I–V curves of these junctions is more precise than previous results using Al–Al2O3–Al tunnel junctions. The chief difficulty with the Al–Al2O3–Al junctions has been the lack of definition in the I–V curves, especially near Tc. Al–Al2O3–Al junctions, in which the energy-gap voltages can be read from the I-V curve with very little ambiguity up to T/Tc ≈ 0.99, are reported here. For the majority of the junctions studied, the temperature dependence of the normalized gap Δ(t)/Δ(0) shows very little scatter (T = 0.34 °K to T = Tc) and agrees closely with the BCS theory. However, a consistent small deviation is observed, with the measured gap values being slightly higher than the BCS prediction. The mean value of 2Δ(0)/kBTc obtained from 21 different junctions is 3.53 with an r.m.s. deviation of ± 0.02.

Superconductivity of very thin aluminium films

1968 ◽  
Vol 46 (9) ◽  
pp. 1129-1132 ◽  
Author(s):  
D. G. Walmsley ◽  
C. K. Campbell ◽  
R. C. Dynes
Keyword(s):  
Transition Temperature ◽  
Temperature Dependence ◽  
Crystallite Size ◽  
Energy Gap ◽  
Superconducting Energy Gap

This note presents the results of superconductive tunneling measurements which show that very thin (50–100 Å) aluminium films exhibit a unique superconducting energy gap. The temperature dependence of this gap is BCS-like, and the ratio of the gap magnitude—as extrapolated to T = 0 °K (2Δ(0))—to the observed transition temperature, Tc, remains close to the usual BCS value of 3.52 k. The effect of crystallite size on deviations from BCS results is also discussed in relation to experimental observations.

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