Effect of impurities on the critical temperature Tc at the upper critical end point of (cyclohexane + methanol)

1988 ◽  
Vol 20 (4) ◽  
pp. 439-445 ◽  
Author(s):  
E Brunner
Author(s):  
Mingyang Du ◽  
Zihan Zhang ◽  
Tian Cui ◽  
Defang Duan

The discovery of the high temperature superconducting state in compounds of hydrogen, carbon and sulfur with the critical temperature (Tc) of 288 K at high pressure is an important milestone...


2013 ◽  
Vol 745-746 ◽  
pp. 261-266 ◽  
Author(s):  
Xin Zhang ◽  
Cui Hua Cheng ◽  
Wen Tao Wang ◽  
Yong Zhang ◽  
Yong Zhao

Epitaxial and textured EuBa2Cu3O7-x(EuBCO) superconductive films were prepared via a F-free polymer-assisted chemical solution deposition (PACSD) method on LaAlO3 (LAO) single crystal substrate in nitrogen atmosphere. Because of the fluorine-free metal organic system, no harmful gas was produced during processing by the PA-CSD method. The film morphorlogy, phase composition, texture and the superconducting critical temperature (Tc) of EuBCO films were investigated by x-ray diffraction (XRD),φ-scan, ω-scan rocking curves, an environmental scanning electron microscope (ESEM) and four-probe method. The Jc value of the EuBCO film in self-field at 77K was measured by using Jc-scan Leipzig system. The results shoed that a denser microstructure and better biaxial texture EuBCO film after a high temperature treatment with a superconducting critical temperature (Tc) of 91K was obtained . The critical current density (Jc) reached 2.4MA/cm2 at 77K in the self-field.


2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Swagata Acharya ◽  
Dimitar Pashov ◽  
Cédric Weber ◽  
Hyowon Park ◽  
Lorenzo Sponza ◽  
...  

AbstractUnconventional superconductivity in $${{\rm{Sr}}}_{2}{{\rm{RuO}}}_{4}$$Sr2RuO4 has been intensively studied for decades. However, the nature of pairing continues to be widely debated. Here we develop a detailed ab initio theory, coupling quasiparticle self-consistent GW approximation with dynamical mean field theory (DMFT), including both local and non-local correlations to address the subtle interplay among spin, charge and orbital degrees of freedom. We report that the superconducting instability has multiple triplet and singlet components. In the unstrained case the triplet eigenvalues are larger than the singlets. Under uniaxial strain, the triplet eigenvalues drop and the singlet components increase. This is concomitant with our observation of spin and charge fluctuations shifting closer to wave-vectors favoring singlet pairing. We identify a complex mechanism where charge fluctuations and spin fluctuations co-operate in the even-parity channel under strain leading to increment in critical temperature (Tc), thus proposing a novel mechanism for pushing the frontier of critical temperature (Tc) in unconventional ‘triplet’ superconductors.


1986 ◽  
Vol 74 ◽  
Author(s):  
J. Koike ◽  
D. E. Oluzzi ◽  
M. Meshii ◽  
P. R. Okamoto

AbstractThe critical dose required to amorphize the crystalline compound CuTi during irradiation with 1 MeV electrons has been investigated from 10 to 288 K. The results show that above a critical temperature (Tc) of about 185 K, CuTi remains crystalline and only defect clusters are formed. Below Tc, amorphization occurs with no observable cluster formation. The critical dose for amorphization was found to be temperature dependent below Tc: as the irradiation temperature increases, a higher dose is required to induce amorphization. This observation supports the concept that Tc corresponds to the vacancy migration temperature. Below Tc, interstitial migration may contribute to the observed reduction in the amorphization rate with increasing temperature.


2008 ◽  
Vol 1099 ◽  
Author(s):  
Andrew Yeung ◽  
Dickon H. L. Ng

AbstractMagnesium diboride (MgB2) was successfully produced in a pellet with sandwich-like structure. The sample was prepared by embedding a layer of Mg powder in between layers of boron powder before they were cold-pressed and sintered in argon atmosphere at different temperatures. After sintering, the interfacial regions between the Mg and B layers were examined and hexagonal platelets were observed lying along the interfacial regions in samples sintered at temperatures above 700°C. These hexagonal platelets were confirmed as MgB2. When samples were sintered at higher temperatures, the lateral size of the platelets increased. At 700°C, the average size of the platelets was 0.5 μgm, and it increased to 1.5 μgm in sample sintered at 900°C. In addition, the critical temperature (TC) and the magnetization (M) were also changed from 35.4 K to 37.1 K and −0.7 to −1.8 emu/g, respectively.


1993 ◽  
Vol 56 (1) ◽  
pp. 2437-2442 ◽  
Author(s):  
H. Mori ◽  
I. Hirabayashi ◽  
S. Tanaka ◽  
T. Mori ◽  
Y. Maruyama ◽  
...  

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