scholarly journals Specific heat of Zn-dopedYBa2Cu3O6.95:Possible evidence for Kondo screening in the superconducting state

2000 ◽  
Vol 61 (5) ◽  
pp. 3604-3609 ◽  
Author(s):  
D. L. Sisson ◽  
S. G. Doettinger ◽  
A. Kapitulnik ◽  
R. Liang ◽  
D. A. Bonn ◽  
...  
Keyword(s):  
Specific Heat ◽  
Superconducting State ◽  
Kondo Screening

SOME HEAVY FERMION SYSTEMS AT VERY LOW TEMPERATURES

1996 ◽  
Vol 10 (04) ◽  
pp. 357-398 ◽  
Author(s):  
ERWIN A. SCHUBERTH
Keyword(s):  
Heat Capacity ◽  
Magnetic Susceptibility ◽  
Magnetic Fields ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Superconducting State ◽  
Heavy Fermion ◽  
Fermion Systems ◽  
Heavy Fermion Systems ◽  
Squid System

The emphasis of this article lies on the properties of heavy fermion systems at the lowest temperatures obtained so far. Methods for measuring specific heat capacity and magnetic susceptibility in the milliKelvin regime are described for both low magnetic fields (<20 mT ) and high fields (<8 T ). Experimental results on UPt 3, UBe 13, and CeCu 6, are presented, and remaining problems are discussed. UPt 3 is widely regarded as the heavy Fermion system which exhibits unconventional superconductivity as demonstrated by the existence of multiple superconducting phases. Whether power laws for instance for the specific heat capacity in the superconducting state extend to T ≈ 0 instead of an exponential behavior as for BCS superconductors is a long-standing question. We have measured the specific heat capacity of several single crystals of UPt 3 in magnetic fields varying from 0 up to 7 T down to a final temperature of 10 mK . Instead of an extended power law a maximum of c(T) occurs around 20 mK, and this maximum persists in magnetic fields above B c2. It is obviously due to a new phase transition which is present both in the normal and in the superconducting state of UPt 3, slightly modified in the latter. Entropy balance above T c is fulfilled if the low-temperature peaks are included. DC-magnetization measurements on two single crystals of UPt 3 in a SQUID system yield a temperature dependence of the penetration depth ~T2 between 150 and 20 mK, considerably extending the temperature range of earlier experiments. Measurements of the anisotropic part of the magnetic susceptibility in a torque-meter indicate an additional phase line from a temperature-dependent anisotropic susceptibility to a T-independent state which is closely connected to the Bc2-line over a wide field range. No indication for a re-entrance of superconductivity is found down to 20 mK. For UBe 13 (in the superconducting state) no specific heat anomaly above 24 mK is found but a deviation from the T2.7 power law valid at higher temperatures. On a single crystal of CeCu 6 dc-magnetization measurements in various magnetic fields in a SQUID system show a plateau of the magnetic susceptibility between 400 and 50 mK, followed by an increase towards lower temperatures. An attempt to fit the low-temperature magnetization curves in several fields between 0.01 mT and 1.6 mT (minus the background from the plateau) with a Brillouin function revealed significant deviations. In 2.7 mT, the highest field applied in this experiment, however, the magnetization can be perfectly fitted assuming a tiny concentration of Gd impurities (1.5 ppm). After subtraction of the contribution due to the Gd 3+ ions from the magnetization curves in each of the lower fields a drop is revealed below 3–5 mK which gets successively quenched by the magnetic field and which has disappeared in 2.7 mT. The specific heat capacity of the same single crystal of CeCu 6 in zero magnetic field shows an increase of c/T from 1.55 J/moleK 2 at higher temperatures up to 2.8 J/moleK 2 at 11 mK. We interpret both results as due to an antiferromagnetic phase transition at 3–5 mK with the peak just not reached in the specific heat experiments.

MÖSSBAUER SPECTRUM AND SUPERCONDUCTIVITY OF SINGLE PHASE EuxY1−xBa2Cu3O9−δ

1987 ◽  
Vol 01 (02) ◽  
pp. 461-464 ◽  
Author(s):  
H.X. Lu ◽  
X.Y. Zhang ◽  
X.K. Gao ◽  
J. Wu ◽  
X.Y. Mao ◽  
...  
Keyword(s):  
High Temperature ◽  
Specific Heat ◽  
Normal State ◽  
Superconducting State ◽  
Single Phase ◽  
X Ray ◽  
Chemical Systems ◽  
Superconducting Compounds ◽  
Zero Resistance ◽  
The Eu

High temperature superconducting compounds in a series of EuxY1−x-Ba2Cu3O9−δ chemical systems, have been prepared and identified, as a single phase. The zero resistance have been determined. X-ray measure ments indicate that the sample is a single phase and Y is replaced by Eu. With Mössbauer spectroscopy, it has been determined that Eu is trivalent and the Eu site is very symmetric. The oxygen sites about Eu are nearly completely occupied. Specific heat has been measured about Eu0.4Y0.6Ba2Cu3O9−δ sample. It is shown that there is a transition from normal state to superconducting state at 90 K with a specific heat change, ΔCp≃20 mJ/g.K.

Magnetic screening and specific heat of an anisotropic Coulomb Bose-gas as a model for the superconducting state

1996 ◽  
Vol 105 (3-4) ◽  
pp. 711-716 ◽  
Author(s):  
Alexandre S. Alexandrov ◽  
William H. Beere ◽  
Victor V. Kabanov
Keyword(s):  
Specific Heat ◽  
Superconducting State ◽  
Bose Gas ◽  
Magnetic Screening

Specific heat of FeSe: Two gaps with different anisotropy in superconducting state

2018 ◽  
Vol 536 ◽  
pp. 785-789 ◽  
Author(s):  
A.V. Muratov ◽  
A.V. Sadakov ◽  
S.Yu. Gavrilkin ◽  
A.R. Prishchepa ◽  
G.S. Epifanova ◽  
...  
Keyword(s):  
Specific Heat ◽  
Superconducting State

scholarly journals The thermodynamic critical field and specific heat of superconducting state in phosphorene under strain

2019 ◽  
Vol 33 (07) ◽  
pp. 1950079
Author(s):  
Kamila A. Szewczyk ◽  
Adam Z. Kaczmarek ◽  
Ewa A. Drzazga
Keyword(s):  
Specific Heat ◽  
Critical Field ◽  
Superconducting State ◽  
Bcs Theory ◽  
High Electron ◽  
Electron Phonon Coupling ◽  
Difference Formula ◽  
Wide Range ◽  
State Formula ◽  
Thermodynamic Critical Field

In this work, we present the thermodynamic properties of the superconducting state in phosphorene. In particular, we have examined the electron doped [Formula: see text] and biaxially strained (4%) monolayer of black phosphorous, which exhibits best thermodynamic stability and highest superconducting critical temperature [Formula: see text] among all monolayer phosphorene structures. Due to the confirmed electron–phonon pairing mechanism and relatively high electron–phonon coupling constant in the studied material, we carried out the calculations in the framework of the Eliashberg formalism for a wide range of the Coulomb pseudopotential [Formula: see text]. We have determined the thermodynamic critical field [Formula: see text], and the specific heat difference [Formula: see text] between superconducting [Formula: see text] and normal state [Formula: see text] as the functions of the temperature. In addition, we have calculated the dimensionless parameters [Formula: see text]/[Formula: see text] and [Formula: see text]/[Formula: see text], and also found their significant deviation from the expectations of the BCS theory. In particular, [Formula: see text] and [Formula: see text] for [Formula: see text].

Sign in / Sign up

Export Citation Format

Share Document