scholarly journals Enhancement of superconducting transition temperature by pointlike disorder and anisotropic energy gap in FeSe single crystals

2016 ◽  
Vol 94 (6) ◽  
Author(s):  
S. Teknowijoyo ◽  
K. Cho ◽  
M. A. Tanatar ◽  
J. Gonzales ◽  
A. E. Böhmer ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Single Crystals ◽  
Superconducting Transition Temperature ◽  
Energy Gap ◽  
Superconducting Transition ◽  
Anisotropic Energy

scholarly journals Research Progress on Ni-Based Antiperovskite Compounds

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
P. Tong ◽  
Y. P. Sun
Keyword(s):  
Phase Diagram ◽  
Transition Temperature ◽  
Single Crystals ◽  
Superconducting Transition Temperature ◽  
Spin Fluctuations ◽  
Research Progress ◽  
Future Research ◽  
Magnetic Element ◽  
Superconducting Transition ◽  
Cubic Structure

The superconductivity in antiperovskite compound MgCNi3was discovered in 2001 following the discovery of the superconducting MgB2. In spite of its lower superconducting transition temperature (8 K) than MgB2(39 K), MgCNi3has attracted considerable attention due to its high content of magnetic element Ni and the cubic structure analogous to the perovskite cuprates. After years of extensive investigations both theoretically and experimentally, however, it is still not clear whether the mechanism for superconductivity is conventional or not. The central issue is if and how the ferromagnetic spin fluctuations contribute to the cooper paring. Recently, the experimental results on the single crystals firstly reported in 2007 trend to indicate a conventionals-wave mechanism. Meanwhile many compounds neighboring to MgCNi3were synthesized and the physical properties were investigated, which enriches the physics of the Ni-based antiperovskite compounds and help understand the superconductivity in MgCNi3. In this paper, we summarize the research progress in these two aspects. Moreover, a universal phase diagram of these compounds is presented, which suggests a phonon-mediated mechanism for the superconductivity, as well as a clue for searching new superconductors with the antiperovskite structure. Finally, a few possible scopes for future research are proposed.

Unrelated BCS-like pairing pseudogap and critical superconducting transition temperature in various cuprate compounds

2018 ◽  
Vol 32 (18) ◽  
pp. 1850195
Author(s):  
S. Dzhumanov ◽  
E. X. Karimboev ◽  
Sh. S. Djumanov
Keyword(s):  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
Order Parameter ◽  
Cuprate Superconductors ◽  
Energy Gap ◽  
Characteristic Temperature ◽  
Superconducting Order Parameter ◽  
Superconducting Transition ◽  
Gap Formation ◽  
Arpes Data

The smooth evolution of the energy gap observed in the tunneling and angle-resolved photoemission spectra (ARPES) of high-[Formula: see text] cuprates with lowering the temperature from a pseudogap state above the critical temperature [Formula: see text] to a superconducting state below [Formula: see text], has been poorly interpreted as the evidence that the pseudogap must have the same origin as the superconducting order parameter, and therefore, must be related to [Formula: see text]. We argue that such an explanation of the tunneling gap and ARPES data is misleading. We show that the BCS-like energy gap (or pseudogap) opening in the electronic excitation spectrum of underdoped-to-overdoped cuprates at a characteristic temperature [Formula: see text] and the true superconducting order parameter appearing only at [Formula: see text] are unrelated. The superconducting phenomenon in unconventional cuprate superconductors is fundamentally different from the BCS-like pairing of fermionic quasiparticles, and the superconducting transition temperature [Formula: see text] is not determined by the BCS-like gap formation. The unusual superconducting order parameter in these high-[Formula: see text] materials appears at [Formula: see text] and coexists with the BCS-like gap (or pseudogap) below [Formula: see text].

Pressure dependence of the superconducting transition temperature in single crystals ofTl2Ba2Ca2Cu3O10−x

1993 ◽  
Vol 47 (9) ◽  
pp. 5524-5527 ◽  
Author(s):  
D. D. Berkley ◽  
E. F. Skelton ◽  
N. E. Moulton ◽  
M. S. Osofsky ◽  
W. T. Lechter ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Single Crystals ◽  
Pressure Dependence ◽  
Superconducting Transition Temperature ◽  
Superconducting Transition

scholarly journals Effect of Multiple Orders on Superconducting Transition Temperature of Hole Doped Cuprates

2017 ◽  
Vol 9 (4) ◽  
pp. 341-349
Author(s):  
I. Qabid ◽  
S. H. Naqib
Keyword(s):  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
Cuprate Superconductors ◽  
Energy Gap ◽  
Density Wave ◽  
Spin Density Wave ◽  
Superconducting Transition ◽  
Electronic Density ◽  
Special Cases ◽  
Multiple Orders

Hole doped high-Tc cuprate superconductors are strongly correlated electronic systems. In these materials, various electronic orders are often found, but whether they support or compete with superconducting order is not unambiguous. Superconductivity normally manifests itself by a superconducting gap in the electronic density of states (EDOS). In cuprates, a gap appears even in the normal state called the pseudogap (PG). For certain doping range, spin density wave and charge density wave coexist with superconductivity by inducing corresponding additional gaps in the EDOS. In this study, we have tried to obtain expression for superconducting transition temperature, Tc by solving the BCS (Bardeen-Cooper-Schrieffer) energy gap equation in the presence of depleted EDOS of various origins and types. We have been successful to solve the weak-coupling BCS integral equation analytically in some special cases and also in the general case by using numerical integration. We have found that depending on conditions these non-pairing gaps/orders can enhance as well as reduce Tc.

Cd additive effect on self-flux growth of Cs-intercalated NbS2 superconducting single crystals

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Masanori Nagao ◽  
Akira Miura ◽  
Yuki Maruyama ◽  
Satoshi Watauchi ◽  
Yoshihiko Takano ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Single Crystals ◽  
Superconducting Transition Temperature ◽  
Additive Effect ◽  
Flux Growth ◽  
Superconducting Transition

Abstract Single crystals of Cs-intercalated NbS2 (Cs x NbS2) were synthesized using a CsCl/KCl self-flux. The size and Cs content of Cs x NbS2 single crystals increased upon adding Cd metal into the starting materials. When 10–30 at% of Cd per Nb was provided in the starting materials, plate-like Cs x NbS2 (x ∼ 0.3) single crystals with 1–2 mm in size and 10–100 μm in thickness were obtained. The superconducting transition temperature of these Cs x NbS2 single crystals was 1.65 K.

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