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.

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.

ELECTRON TUNNELING MEASUREMENTS OF ENERGY GAP IN SUPERCONDUCTORS YBaCuO, LaSrCuO AND BPBO

1987 ◽  
Vol 01 (02) ◽  
pp. 555-559 ◽  
Author(s):  
Hongjie TAO ◽  
Yingfei CHEN ◽  
Li LU ◽  
Qiansheng YANG ◽  
Bairu ZHAO ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Strong Coupling ◽  
Perovskite Structure ◽  
Energy Gap ◽  
Electron Tunneling ◽  
Point Contact ◽  
Tunneling Conductance ◽  
Temperature Ratio ◽  
Superconducting Energy Gap

We have carried out superconducting energy gap measurements for polycrystalline perovskite-structure superconductors YBaCuO, LaSrCuO and BPBO with point contact tunneling. The tunneling conductance curves for YBaCuO, LaSrCuO and BPBO show the energy gap to transition temperature ratio 2Δ/kTc =4.7, 7.8 and 5.05 respectively, which is consistant with the strong-coupling superconductivity.

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.

Superconducting energy gap of NbS2

1984 ◽  
Vol 62 (8) ◽  
pp. 776-779 ◽  
Author(s):  
R. J. Kennedy ◽  
B. P. Clayman
Keyword(s):  
Magnetic Susceptibility ◽  
Transition Temperature ◽  
Energy Gap ◽  
Far Infrared ◽  
The Novel ◽  
Superconducting Transition ◽  
Small Particles ◽  
Energy Gaps ◽  
Superconducting Energy Gap ◽  
Novel Method

The superconducting energy gaps of small particles (1–10 μm) of 2H–NbS2 and 2H–NbSe2 have been measured by far-infrared (FIR) transmission spectroscopy. Comparison of these results with previous FIR measurements made on millimetre-size single crystals of 2H–NbSe2 validates the use of the novel method of sample preparation used here. Comparison of the gap frequencies (νg) with the superconducting transition temperature (Tc) determined by magnetic susceptibility measurements indicates that 2H–NbS2, unlike 2H–NbSe2, exhibits non-Bardeen–Cooper–Schrieffer (BCS)-like behaviour, with hνg/kTc = 2.3.

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