UNCONVENTIONAL SUPERCONDUCTIVITY IN UPt3: FREQUENCY DEPENDENT AC SUSCEPTIBILITY

1993 ◽  
Vol 07 (01n03) ◽  
pp. 18-21
Author(s):  
Z. KOZIOL ◽  
J. J. M. FRANSE ◽  
A. A. MENOVSKY
Keyword(s):  
Normal State ◽  
Surface Resistance ◽  
Skin Effect ◽  
Ac Susceptibility ◽  
Response Characteristic ◽  
Complex Conductivity ◽  
Unconventional Superconductivity ◽  
Superconducting Transition ◽  
Good Qualitative Agreement ◽  
Unconventional Superconductor

A method has been developed for measuring and analysing the complex ac susceptibility of a metal undergoing a superconducting transition, in case there exists an interplay between the normal-state skin-effect and the response characteristic for the superconducting state. For the unconventional superconductor UPt 3, the study of the temperature and frequency dependence of the complex conductivity close to T c has resulted in predictions for the surface resistance and the radio-frequency susceptibility which are in a good qualitative agreement with published experimental results.

Femtosecond Pump-probe studies of Carrier Dynamics in the Normal State of the Unconventional Superconductor Sr2RuO4

2004 ◽  
Vol 850 ◽  
Author(s):  
P. Guptasarma ◽  
S. L. Sendelbach ◽  
M. L. Schneider ◽  
M. S. Williamsen ◽  
G. Taft ◽  
...  
Keyword(s):  
Normal State ◽  
Superconducting State ◽  
Condensed Matter ◽  
Carrier Dynamics ◽  
Unconventional Superconductivity ◽  
Critical Transition ◽  
Critical Transition Temperature ◽  
Unconventional Superconductor ◽  
Pump Probe ◽  
Microscopic Origin

The microscopic origin of unconventional superconductivity1 is one of the most fascinating questions2–3 in condensed matter physics. In recent years, important questions have been raised about the nature of the normal (metallic, non-superconducting) state above the superconducting critical transition temperature (Tc). In fact, it is now generally agreed4,5 that a better understanding of the nature of the normal state is crucial to our understanding of the microscopic origin of the superconducting state.

Electron Irradiation of YBa2Cu3O7 at low Temperatures

1987 ◽  
Vol 99 ◽  
Author(s):  
B. Stritzker ◽  
W. Zander ◽  
F. Dworschak ◽  
U. Poppe ◽  
K. Fischer
Keyword(s):  
Transition Temperature ◽  
Electron Irradiation ◽  
Normal State ◽  
Low Temperatures ◽  
Superconducting Transition Temperature ◽  
Superconducting Transition ◽  
Radiation Induced ◽  
State Resistance ◽  
Normal State Resistance

ABSTRACTBulk samples of YBa2Cu3O7−x have been homogenously irradiated with 3 MeV electrons at temperatures below 20 K. Whereas the superconducting transition temperature, Tc, drops dramatically with increasing dose the width of the transition remains unchanged (Δ Tc ≤ 1.5 K). The normal state resistance at 100 K increases substantially during the electron irradiation. Several irreproducible experiments can be interpreted with a radiation induced, unstable increase of Tc.

Scaling of Complex Conductivity for A Percolating Metal-Insulator Composite with Inter granular Tunneling Above and Below the Superconducting Transition

1995 ◽  
Vol 411 ◽  
Author(s):  
D. S. Mclachlan ◽  
A. B. Pakhomov ◽  
I. I. Oblachova ◽  
F. Brouers ◽  
A. Sarychev
Keyword(s):  
Volume Fraction ◽  
Frequency Dispersion ◽  
Scaling Theory ◽  
Complex Conductivity ◽  
Superconducting Transition ◽  
Percolation Transition ◽  
Metal Insulator ◽  
Metal Volume ◽  
Metal Volume Fraction ◽  
Composite Samples

ABSTRACTThe complex conductivity was measured on 3d granular NbC-KCI composite samples at varying metal volume fraction p, frequency ω and temperature above and below the superconductivity critical Tc. The observed frequency dispersion is anomalous in that it is not in accord with the scaling theory of percolation transition. The results are compared with a recently developed scaling theory, which takes both intercluster tunneling and intercluster capacitance into account. The experimental estimates for the new critical exponents are in reasonable agreement with the theory. The very low value of the crossover frequency can also be understood. We also present the data showing the dispersion of the complex conductivity well below the superconducting transition Tc of NbC.

THE EFFECT OF PARTIAL ATOMIC SUBSTITUTION ON ELECTRIC AND MAGNETIC PROPERTIES OF (Bi,Pb):2223 SINTERED SUPERCONDUCTORS

2003 ◽  
Vol 17 (26) ◽  
pp. 4675-4681 ◽  
Author(s):  
A. V. POP ◽  
M. POP ◽  
I. I. GERU
Keyword(s):  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Electrical Resistance ◽  
Ac Susceptibility ◽  
Partial Substitution ◽  
Superconducting Transition ◽  
Ac Magnetic Susceptibility ◽  
Atomic Concentration ◽  
Susceptibility Data ◽  
Atomic Substitution

The effect of partial substitution of Ca by x = 0.02 La on the electrical and magnetically properties of two (Bi,Pb):2223 superconductor ceramic S1 and S2 (with different Pb and Sr atomic concentration) were investigated by using electrical resistance and AC magnetic susceptibility measurements. The parameters from linear resistivity data in the normal state and superconducting transition are sensitive to the compounds stoechiomerty. The intergrain critical current density JcJ(T) dependence near Tc obtained from immaginary AC susceptibility data agrees with the assumption of SNS intergrain junctions.

Superconductivity and Magnetic Ordering of Pr in CaLa1-xPrxBaCu3O7 System

1997 ◽  
Vol 11 (07) ◽  
pp. 323-331 ◽  
Author(s):  
V. P. S. Awana ◽  
Rajvir Singh ◽  
D. A. Landinez Tellez ◽  
J. M. Ferreira ◽  
J. Albino Aguiar ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Normal State ◽  
Ac Susceptibility ◽  
Magnetic Ordering ◽  
X Ray Diffraction ◽  
X Ray ◽  
Antiferromagnetic Ordering ◽  
Peak Intensity ◽  
Heat Capacity Measurements ◽  
A Minor

We present the results of superconductivity, normal state magnetic susceptibility and heat capacity measurements on the tetragonal CaLa 1-x Pr x BaCu 3 O 7 compound. Ac susceptibility measurements show that the transition temperature T c of the unsubstituted sample decreases with an increase in the Pr concentration. Normal state dc magnetic susceptibility measurements performed in an applied field of 0.5 T show a Curie–Weiss behaviour in terms of the paramagnetic moment of Pr. The effective paramagnetic moment of Pr appears to be intermediate between those of the free Pr 3+ and Pr 4+ ions. For the nonsuperconducting samples i.e., x = 0.70 and 1.0, we observe an antiferromagnetic ordering temperature T N of nearly 4 K and 8 K respectively. The X-ray diffraction results show that the CaPrBaCu 3 O 7 compound is free from other phases, having a minor (less than 8%, in terms of peak intensity) impurity phase. The lower T N (8 K) of PrBaCaCu 3 O 7 as compared to the known antiferromagnetic ordering temperature of 17 K for PrBa 2 Cu 3 O 7 indicates a less deleterious effect of Pr in the present case.

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.

scholarly journals Structural and Superconducting Properties of Thermal Treatment-Synthesised Bulk YBa2Cu3O7−δ Superconductor: Effect of Addition of SnO2 Nanoparticles

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 92 ◽  
Author(s):  
Nur Mohd Yusuf ◽  
Mohd Awang Kechik ◽  
Hussein Baqiah ◽  
Chen Soo Kien ◽  
Lim Kean Pah ◽  
...  
Keyword(s):  
Thermal Treatment ◽  
Ac Susceptibility ◽  
Sno2 Nanoparticles ◽  
Treatment Method ◽  
Composition Analysis ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
Bulk Superconductors ◽  
Diamagnetic Transition ◽  
Critical Temperature Tc

YBa2Cu3O7−δ (Y-123) bulk superconductors with the addition of (0.0, 0.2, 0.4, 0.6, 0.8, and 1.0 wt.%) SnO2 nanoparticles were synthesised via a thermal treatment method. The influence of SnO2 addition on the superconducting properties by means of critical temperature, Tc, AC susceptibility, phase formation and microstructures, including its elemental composition analysis, were studied. Sharp superconducting transition, ∆Tc, and diamagnetic transition were obtained for all SnO2-added samples. It was observed that sample x = 0.4 with a Y-123 phase percentage of 95.8% gives the highest Tc, smallest ∆Tc, and the sharpest diamagnetic transition in the normalised susceptibility curves. The microstructure also showed an excess of Sn precipitates on the sample’s surface at x = 0.8 and above. As such, the best superconducting properties were observed at x = 0.4 SnO2 addition inside the Y-123 host sample.

scholarly journals Observation of half-quantum flux in the unconventional superconductor β-Bi2Pd

Science ◽  
2019 ◽  
Vol 366 (6462) ◽  
pp. 238-241 ◽  
Author(s):  
Yufan Li ◽  
Xiaoying Xu ◽  
M.-H. Lee ◽  
M.-W. Chu ◽  
C. L. Chien
Keyword(s):  
Magnetic Flux ◽  
Pairing Symmetry ◽  
Quantum Oscillation ◽  
Unconventional Superconductivity ◽  
Unconventional Superconductor ◽  
Quantum Bits ◽  
Flux Quantization ◽  
Triplet Pairing ◽  
Quantum Flux ◽  
Spin Triplet

Magnetic flux quantization is one of the defining properties of a superconductor. We report the observation of half-integer magnetic flux quantization in mesoscopic rings of superconducting β-Bi2Pd thin films. The half-quantum fluxoid manifests itself as a π phase shift in the quantum oscillation of the superconducting critical temperature. This result verifies unconventional superconductivity of β-Bi2Pd and is consistent with a spin-triplet pairing symmetry. Our findings may have implications for flux quantum bits in the context of quantum computing.

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