scholarly journals Effect of van Hove singularity on the isotope effect and critical temperature of H3S hydride superconductor as a function of pressure

2021 ◽  
pp. 110451
Author(s):  
S. Villa-Cortés ◽  
O. De la Peña-Seaman
Keyword(s):  
Critical Temperature ◽  
Isotope Effect ◽  
Van Hove Singularity

Effect of pseudogap and van Hove singularity density of state on the isotope effect coefficient of superconductor

2018 ◽  
Vol 32 (11) ◽  
pp. 1850130 ◽  
Author(s):  
Thaipanya Chanpoom
Keyword(s):  
Experimental Data ◽  
High Temperature ◽  
Critical Temperature ◽  
Isotope Effect ◽  
High Temperature Superconductors ◽  
Numerical Results ◽  
Density Of State ◽  
Van Hove Singularity

This research was to study the isotope effect coefficient of high temperature superconductors taking into account the pseudogap. We used the BCS-like model including the effect of the vHs density of state and pseudogap. The isotope effect coefficient was derived to the analytical and the approximation form. For the effect of vHs density of state, we found that the isotope effect coefficient increased as the critical temperature increased. For the pseudogap effect, as the critical temperature increased, the isotope effect coefficient decreased to the BCS value, 0.5. For the effect of the vHs density of state and pseudogap, we found that when the critical temperature increased, the isotope effect coefficient decreased. Finally, we showed our numerical results that can fit well with the experimental data of YBa[Formula: see text]La[Formula: see text]Cu3O[Formula: see text] and Y[Formula: see text]Pr[Formula: see text]Ba2Cu3O[Formula: see text] superconductors.

The investigation on anomalous isotope effect coefficient of LaSrCuO superconductor

2019 ◽  
Vol 33 (31) ◽  
pp. 1950379
Author(s):  
P. Mycharoen ◽  
P. Udomsamuthirun
Keyword(s):  
Experimental Data ◽  
Critical Temperature ◽  
Temperature Dependence ◽  
Isotope Effect ◽  
Weak Coupling ◽  
Numerical Results ◽  
Coupling Method ◽  
Density Of State ◽  
Van Hove Singularity ◽  
Weak Coupling Method

In this research, the anomalous isotope effect coefficient of LaSrCuO superconductor was investigated in the weak-coupling method. The constant and van Hove singularity density of state, pseudogap, and the form of pseudogap temperature dependence on critical temperature are included in our calculation. Finally, the numerical results are shown in comparison with the experimental data of LaSrCuO superconductor. We found that the van Hove singularity density of state and the inversely relation of pseudogap temperature and critical temperature can fit well with the anomalous isotope effect coefficient data of LaSrCuO superconductor.

Oxygen isotope effect on critical temperature and phonon modes inYBa2Cu3O7

1988 ◽  
Vol 38 (7) ◽  
pp. 5025-5027 ◽  
Author(s):  
E. L. Benitez ◽  
J. J. Lin ◽  
S. J. Poon ◽  
W. E. Farneth ◽  
M. K. Crawford ◽  
...  
Keyword(s):  
Critical Temperature ◽  
Oxygen Isotope ◽  
Isotope Effect ◽  
Phonon Modes

scholarly journals Critical Temperature and Enhanced Isotope Effect in the Presence of Paramagnons in Phonon-Mediated Superconductors

2005 ◽  
Vol 95 (25) ◽  
Author(s):  
O. V. Dolgov ◽  
I. I. Mazin ◽  
A. A. Golubov ◽  
S. Y. Savrasov ◽  
E. G. Maksimov
Keyword(s):  
Critical Temperature ◽  
Isotope Effect

Anomalous isotope effect and Van Hove singularity in superconducting Cu oxides

1990 ◽  
Vol 65 (21) ◽  
pp. 2724-2727 ◽  
Author(s):  
C. C. Tsuei ◽  
D. M. Newns ◽  
C. C. Chi ◽  
P. C. Pattnaik
Keyword(s):  
Isotope Effect ◽  
Van Hove Singularity

THEORY OF THE ISOTOPE EFFECT AND SUPERCONDUCTING TRANSITION TEMPERATURE IN HIGH-Tc OXIDES

2011 ◽  
Vol 25 (26) ◽  
pp. 2069-2078 ◽  
Author(s):  
A. BECHLAGHEM ◽  
D. BOURBIE
Keyword(s):  
Experimental Data ◽  
Transition Temperature ◽  
Fermi Level ◽  
Isotope Effect ◽  
Qualitative Agreement ◽  
Superconducting Transition Temperature ◽  
Superconducting Transition ◽  
Van Hove Singularity ◽  
High Tc ◽  
Analytical Expressions

Analytical expressions for the superconducting transition temperature Tc and the isotope coefficient α have been obtained for the case where the Fermi level is close to the van Hove singularity. In this approach, we consider two interactions, the first related to the phonons and the second relevant to the magnetic excitations. Our result shows that the isotope coefficient α decreases with the superconducting transition temperature Tc in qualitative agreement with experimental data.

scholarly journals ENHANCEMENT OF SUPERCONDUCTIVE CRITICAL TEMPERATURES IN ALMOST EMPTY OR FULL BANDS IN TWO DIMENSIONS: POSSIBLE RELEVANCE TO β-HfNCl, C60 AND MgB2

2001 ◽  
Vol 15 (12n13) ◽  
pp. 359-368 ◽  
Author(s):  
MAHITO KOHMOTO ◽  
IKSOO CHANG ◽  
JACQUES FRIEDEL
Keyword(s):  
Critical Temperature ◽  
Field Effect ◽  
Field Effect Transistor ◽  
Two Dimensions ◽  
Bcs Theory ◽  
Van Hove Singularity ◽  
Critical Temperatures ◽  
Non Local ◽  
Effect Transistor ◽  
First Time

We examine the possibility of enhancement of superconductive critical temperature in two-dimensions using the BCS theory. When the Fermi level is near an edge of a band the density of states (DOS) is not particularly high but k-dependent contribution to DOS (electron density on the Fermi surface) has a divergent peak at the bottom or top of the band (van Hove singularity). The attractive phonon-mediated interaction depends on q (momentum transfer) due to finite screening (non-local interaction). Enhancement of the critical temperatures is shown for the first time in this case. The results are qualitatively consistent with the superconductive behaviors of HfNCl (T c ≤ 25 K ) and ZrNCl (T c ≤ 15 K ), C 60 with a field-effect transistor configuration (T c = 52 K ), and MgB 2 (T c ≈ 40 K ) which have unexpectedly high critical temperatures.

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