Direct determination of the Andreev reflection probability by means of point contact spectroscopy

2000 ◽  
Vol 76 (9) ◽  
pp. 1152-1154 ◽  
Author(s):  
M. Jakob ◽  
H. Stahl ◽  
J. Knoch ◽  
J. Appenzeller ◽  
B. Lengeler ◽  
...  
Keyword(s):  
Andreev Reflection ◽  
Point Contact ◽  
Direct Determination ◽  
Point Contact Spectroscopy ◽  
Reflection Probability

scholarly journals POINT-CONTACT SPECTROSCOPY OF MAGNESIUM DIBORIDE WITH DIFFERENT COUNTER-ELECTRODES

2003 ◽  
Vol 17 (27n28) ◽  
pp. 1405-1416
Author(s):  
A. I. D'YACHENKO ◽  
V. YU. TARENKOV ◽  
M. A. BELOGOLOVSKII ◽  
V. N. VARYUKHIN ◽  
A. V. ABAL'OSHEV ◽  
...  
Keyword(s):  
Andreev Reflection ◽  
Magnesium Diboride ◽  
Three Dimensional ◽  
Point Contact ◽  
Band Model ◽  
Counter Electrodes ◽  
Break Junctions ◽  
Point Contact Spectroscopy ◽  
Dc Current ◽  
Two Band Model

We report on tunneling and Andreev-reflection conductance spectra of 39 K superconducting magnesium diboride, obtained with Pb and Au counter-electrodes. Two distinct steps at close to 2.7 and 7.1 meV appear in a low-resistance metallic-type Au–MgB 2 junction characteristic, whereas a tunneling-like spectrum measured for the same junction, annealed by the application of DC current, exhibits only a rounded contribution of the larger gap. Junctions with a superconducting lead counter-electrode pressed into a bulk MgB 2 sample reveal two conductance peaks that are interpreted as the result of the formation of a highly-transmitting break junctions inside the magnesium diboride ceramic. Our results strongly support the two-band model with two different gap values on quasi-two-dimensional σ (7.1 meV) and three-dimensional π (2.7 meV) Fermi surface sheets of MgB 2.

Sharp gap edge and determination of the fermi velocity in Y1Ba2Cu3O7?? by point contact spectroscopy

1992 ◽  
Vol 5 (2) ◽  
pp. 191-194 ◽  
Author(s):  
Nir Mass ◽  
D. Ilzycer ◽  
G. Deutscher ◽  
G. Desgardin ◽  
I. Monot ◽  
...  
Keyword(s):  
Point Contact ◽  
Fermi Velocity ◽  
Point Contact Spectroscopy

scholarly journals Independent determination of the two gaps by directional point-contact spectroscopy in MgB2single crystals

2002 ◽  
Vol 16 (2) ◽  
pp. 171-175 ◽  
Author(s):  
R S Gonnelli ◽  
D Daghero ◽  
G A Ummarino ◽  
V A Stepanov ◽  
J Jun ◽  
...  
Keyword(s):  
Point Contact ◽  
Point Contact Spectroscopy ◽  
Independent Determination

scholarly journals Determination of the spin polarization of RFe2 (R = Dy, Er, Y) by point contact Andreev reflection

2012 ◽  
Vol 111 (6) ◽  
pp. 063917 ◽  
Author(s):  
C. Morrison ◽  
D. Wang ◽  
G. J. Bowden ◽  
R. C. C. Ward ◽  
P. A. J. de Groot
Keyword(s):  
Spin Polarization ◽  
Andreev Reflection ◽  
Point Contact

POINT CONTACT SPECTROSCOPY IN ORIENTED YBa2Cu3O7−δ

1993 ◽  
Vol 07 (01n03) ◽  
pp. 127-130
Author(s):  
NIR HASS ◽  
D. ILZYCER ◽  
G. DEUTSCHER ◽  
G. DESGARDIN ◽  
I. MONOT ◽  
...  
Keyword(s):  
High Temperature Superconductors ◽  
Point Contact ◽  
Theoretical Explanation ◽  
Precise Determination ◽  
Fermi Velocity ◽  
Zero Bias ◽  
Point Contact Spectroscopy ◽  
Out Of Plane ◽  
Plane Direction

We report point contact spectroscopy measurements on YBa 2 Cu 3 O 7−δ thin films and textured bulk ceramics. The I(V) curves measured along the Copper-Oxygen (ab) plane direction are characteristic of the Andreev reflection phenomenon, with a sharp break at the gap edge. This allows a rather precise determination of the (in plane) gap, Δ = 20 mev . Subgap structure suggests the existence of a smaller gap for some orientations in the (ab) plane, of the order of 12 mev. The data also enabled us to set a lower bound to the inplane Fermi velocity in YBa 2 Cu 3 O 7−δ: v F ≥ 7 × 107 cm/sec . The value of v F has a crucial importance in the determination of the theoretical explanation for superconductivity in the High Temperature Superconductors. For out of plane measurements, only a weak zero bias anomaly is observed at energies up to 5 mev.

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