Tunneling Measurements of Density of States in Superconducting YBa2Cu3Oy

1987 ◽  
Vol 99 ◽  
Author(s):  
K.I Ida ◽  
K. Gotoh ◽  
H. Enomoto ◽  
Y. Takano ◽  
N. Mori ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Temperature Dependence ◽  
Density Of States ◽  
High Tc ◽  
Temperature Range ◽  
High Tc Superconductor

ABSTRACTTunneling measurements were applied to investigate the density of states of the high Tc superconductor in the temperature range from 4.2 K to the transition temperature. Several structures were found in conductance curves in higher bias region than ever reported, and they vanished around Tc. Temperature dependence of the bias voltages at which these structures appeared showed the BCS-like behavior.

A Device for Measuring High-TC Superconductor Transition Temperature with Electric Transport and AC Susceptibility Methods Based on Small Cryocooler Cooling

2013 ◽  
Vol 745-746 ◽  
pp. 152-157 ◽  
Author(s):  
San Sheng Wang ◽  
Xiao Shuai Ning ◽  
Xiang Hua Chu ◽  
Hua Li
Keyword(s):  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
Ac Susceptibility ◽  
Transition Curve ◽  
Secondary Coil ◽  
Electric Transport ◽  
Superconducting Transition ◽  
High Tc ◽  
High Tc Superconductor ◽  
Lock In

A device for measuring high-TC superconducting transition temperature in a small cryocooler is described which allows a samples temperature to fall steadily from room temperature to 45K. This cryocooler not only meets the high-TC superconductors measurement requirements, but also yields accurate measurement results under ambient conditions. In this device, two measurement methods for measuring high-TC superconducting transition temperature are applied: the electric transport and the AC susceptibility. The former adopts a four-wire method to eliminate the contact resistance between the leads and the sample. During the measurement process the current reversal method for datum processing is applied to eliminate the thermoelectric voltages; this ensures the repeatability error less than 0.4K in the measurement of the superconducting transition temperature. The AC susceptibility method adopts a lock-in amplifier to provide an AC voltage signal for the primary coil, and then lock-in amplifier is used to measure the electrical signals of the secondary coil according to the AC magnetic susceptibility values. The advantage of this device is that by merely changing the position of the sample in the vacuum chamber, the R-T curve and the χ-T curve of a superconducting sample in the same temperature range can be automatically recorded, which provides reliable data for high-TC superconductor transition curve measurement.

Temperature dependence of Doppler broadening of the annihilation line in a high Tc superconductor

1988 ◽  
Vol 128 (1-2) ◽  
pp. 97-99 ◽  
Author(s):  
Stef. Charalambous ◽  
M. Chardalas ◽  
Sp. Dedoussis ◽  
C. Elefteriades ◽  
A.K. Liolios ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Doppler Broadening ◽  
High Tc ◽  
Annihilation Line ◽  
High Tc Superconductor

HIGH MAGNETIC FIELD HALL EFFECT AND MAGNETORESISTANCE STUDIES OF Y-Ba-Cu-O: A HIGH Tc SUPERCONDUCTOR

1987 ◽  
Vol 01 (02) ◽  
pp. 413-417
Author(s):  
J.D. Hettinger ◽  
A.G. Swanson ◽  
J.S. Brooks ◽  
Y.P. Ma
Keyword(s):  
Magnetic Field ◽  
High Temperature ◽  
Transition Temperature ◽  
Hall Effect ◽  
High Temperature Superconductor ◽  
Strong Dependence ◽  
Zero Magnetic Field ◽  
High Tc ◽  
Relative Percentage ◽  
High Tc Superconductor

We have measured the transition temperature, critical field, magnetoresistance, and Hall effect for the high temperature superconductor Y-Ba-Cu-O in magnetic fields up to 23T in the temperature range 4.2 to 125K. Meissner studies at zero magnetic field were also performed in some cases. We find a strong dependence of these parameters on the relative percentage of the correct phase of Y-Ba-Cu-O in the sample. We report new results on magnetoresistance and Hall effect in these materials.

Temperature Dependence of the O2-Oscillation Pattern in the Filamentous Cyanobacterium Oscillatoria chalybea and in Chlorella kessleri

1996 ◽  
Vol 51 (11-12) ◽  
pp. 823-832 ◽  
Author(s):  
K Burda ◽  
P He ◽  
K. P Bader ◽  
G. H Schmid
Keyword(s):  
Transition Temperature ◽  
Temperature Dependence ◽  
Oxygen Evolution ◽  
Filamentous Cyanobacterium ◽  
State Distribution ◽  
Oscillation Pattern ◽  
Chlorella Kessleri ◽  
Temperature Range ◽  
Oscillatoria Chalybea ◽  
Oxygen Evolving

Abstract Five characteristic discontinuities of the pattern of oxygen evolution have been detected for the filamentous cyanobacterium Oscillatoria chalybea in the temperature range of 0°C to 30°C. The temperatures at which these discontinuities occur are: ≈ 5°C, ≈ 11°C, ≈ 15°C, ≈ 21°C and ≈ 25°C. The calculated initial 5-S state distribution, the miss parameter and the fraction of the fast transition S3 → S0+ O2 are affected. The discontinuities are observed at the same transition temperature also for Chlorella kessleri hence are not specific for the cyanobacterium. Based on these studies it is concluded that the not vanishing oxygen signal under the first flash of a flash train in Oscillatoria cannot have its origin in interactions between oxygen-evolving complexes. A decrease of temperature should slow down the expected charge exchanges, improve the oscillations, thus reduce or lower the first two oxygen amplitudes of the oscillatoria pattern. Lowering of the temperautres improves the oscillations but does not lower the first O2 signal of the pattern.

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.

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