Study on the Relationship between Uniaxial Strain and Critical Transition Temperature of MgB2 Based on First-principles

2021 ◽  
Author(s):  
Yong Yang ◽  
Tianbao Yue ◽  
Shenglong Wang
Keyword(s):  
Transition Temperature ◽  
Charge Density ◽  
First Principles ◽  
Phonon Dispersion ◽  
Uniaxial Strain ◽  
Superconducting Materials ◽  
Critical Transition ◽  
Critical Transition Temperature ◽  
Electronic Band ◽  
The Relationship

Abstract It has been shown that the critical transition temperature (Tc) of MgB2 superconducting materials decreases with the increase of hydrostatic pressure, but this is a comprehensive Tc change after multiaxial strain, and the influence of strain on Tc is not clearly understood. In this paper, based on the McMillan superconducting calculation formula and the first-principles density functional theory, the Tc change of MgB2 under uniaxial strain and the properties of MgB2 such as energy band, Fermi surface, differential charge density and phonon dispersion spectrum under uniaxial strain are studied, and the relationship between uniaxial strain and these properties is analyzed. The calculated Tc of MgB2 at zero strain is 38.35 K, which is in good agreement with the experimental value of 39 K. When the a-axis strain is 1%, the Tc value can be increased to 49.7 K, and there is a further improvement trend. When the a-axis compression strain is -1%, Tc decreases to 31.52 K. When the c-axis tensioncompression strain is applied, the change of Tc value is small. Further analysis shows that the influence of a-axis strain on the differential charge density, electronic band structure, phonon dispersion and other properties of MgB2 is significantly greater than that of c-axis strain, and the influence of these properties on Tc is discussed. The work in this paper has certain theoretical and guiding significance for the preparation of MgB2 with higher Tc and the study of the effect of uniaxial strain on Tc of superconducting materials.

Correlation between oxygen excess density and critical transition temperature in superconducting Bi-2201, Bi-2212 and Bi-2223

2008 ◽  
Vol 63 (11-12) ◽  
pp. 1372-1375 ◽  
Author(s):  
H.P. Roeser ◽  
F. Hetfleisch ◽  
F.M. Huber ◽  
M.F. von Schoenermark ◽  
M. Stepper ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Critical Transition ◽  
Critical Transition Temperature ◽  
Excess Density ◽  
Oxygen Excess

Reformulation of pairing theory

1988 ◽  
Vol 02 (05) ◽  
pp. 1101-1105 ◽  
Author(s):  
Miklos GULACSI ◽  
Zsolt GULACSI
Keyword(s):  
Transition Temperature ◽  
Size Effect ◽  
Layer Thickness ◽  
Short Communication ◽  
Cooper Pairing ◽  
Two Dimensional ◽  
Critical Transition ◽  
Critical Transition Temperature ◽  
Quantum Size ◽  
Natural Way

The original Cooper pairing theory is reformulated for electrons confined in a layer. This analysis is motivated by the quasi-two-dimensional character of the oxidic superconductors, in case of which the extension of the initial (3D) Cooper framework is practically impossible. By considering the electrons moving in a flat box, due to quantum size effect the properties of these oxidic superconductors can be explained in a natural way. In this short communication we will concentrate to the variation of the critical transition temperature due to the layer thickness and to the number of conduction (Cu-O) planes. The results are confirmed by the experiment. This being an evidence for the presence of the charge confinement effect in the oxidic superconductors.

A link between critical transition temperature and the structure of superconducting

2008 ◽  
Vol 62 (12) ◽  
pp. 733-736 ◽  
Author(s):  
H.P. Roeser ◽  
F. Hetfleisch ◽  
F.M. Huber ◽  
M.F. von Schoenermark ◽  
M. Stepper ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Critical Transition ◽  
Critical Transition Temperature

BSCCO 2212 Defective Tellurium Ions on Bi-Site

2011 ◽  
Vol 319-320 ◽  
pp. 161-166 ◽  
Author(s):  
Morsy M.A. Sekkina ◽  
M. El-Hofy ◽  
Khaled M. Elsabawy ◽  
M. Bediwy
Keyword(s):  
Electrical Conductivity ◽  
Transition Temperature ◽  
Critical Transition ◽  
Chemical Formula ◽  
Hole Filling ◽  
Critical Transition Temperature ◽  
Solid State Reaction Technique ◽  
Conventional Solid State Reaction ◽  
Major Phase ◽  
Dc Electrical Conductivity

BSCCO 2212 superconducting samples, doped Tellurium, with the chemical formula Bi2-xTexSr2CaCu2O8, were prepared by the conventional solid state reaction technique. The prepared samples were studied utilizing XRD, DC-electrical conductivity and SEM. XRD spectra indicated that 2212 with tetragonal structure is the major phase, whereas Bi-2201 and CaTeO4 are minor phases. At higher Te-additions x, traces from some other semi conducting phases were detected. The critical transition temperature Tcoffset was found to decrease non-linearly with x, which attributed to the hole filling caused by the liberated electrons of Te4+ ions. For x–values in the range 0.1 ≤ x ≤ 0.4, the steepness of (ρ vs T) relationship increases abruptly around 150 K; this was attributed to change in the oxygen vacancy feature (phase-like transition). SEM photographs revealed that as Te-content increases the compactness of the surface and the connectivity of the grains decreases, while pores and voids increase as a result of decreasing the amount of Bi and presence of multiple-phases in the sample.

scholarly journals Gap Structure of the Overdoped Iron-Pnictide Superconductor Ba(Fe0.942Ni0.058)2As2: A Low-Temperature Specific-Heat Study

2015 ◽  
Vol 2015 ◽  
pp. 1-5
Author(s):  
Gang Mu ◽  
Bo Gao ◽  
Xiaoming Xie ◽  
Yoichi Tanabe ◽  
Jingtao Xu ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Low Temperature ◽  
Specific Heat ◽  
Energy Gap ◽  
Critical Transition ◽  
Critical Transition Temperature ◽  
Iron Pnictide ◽  
Iron Pnictide Superconductor ◽  
Low Temperature Specific Heat ◽  
Co Doped

Low-temperature specific heat (SH) is measured on the postannealed Ba(Fe1−xNix)2As2single crystal withx= 0.058 under different magnetic fields. The sample locates on the overdoped sides and the critical transition temperatureTcis determined to be 14.8 K by both the magnetization and SH measurements. A simple and reliable analysis shows that, besides the phonon and normal electronic contributions, a clearT2term emerges in the low temperature SH data. Our observation is similar to that observed in the Co-doped system in our previous work and is consistent with the theoretical prediction for a superconductor with line nodes in the energy gap.

scholarly journals IMPACT OF Zn SUBSTITUTION ON PHASE FORMATION AND SUPERCONDUCTIVITY OF Bi1.6Pb0.4Sr2Ca2Cu3-xZnxO10-δ WITH x = 0.0, 0.015, 0.03, 0.06, 0.09 AND 0.12

2005 ◽  
Vol 19 (16) ◽  
pp. 771-778 ◽  
Author(s):  
R. B. SAXENA ◽  
RAJIV GIRI ◽  
V. P. S. AWANA ◽  
H. K. SINGH ◽  
M. A. ANSARI ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Transition Temperature ◽  
Lattice Parameter ◽  
Ac Magnetic Susceptibility ◽  
Critical Transition ◽  
Critical Transition Temperature ◽  
Reaction Route ◽  
Zn Doping ◽  
Zn Substitution ◽  
Solid State Reaction Route

Samples of series Bi 1.6 Pb 0.4 Sr 2 Ca 2 Cu 3-x Zn x O 10-δ with x = 0.0, 0.015, 0.03, 0.06, 0.09 and 0.12 are synthesized by solid-state reaction route. All the samples crystallize in tetragonal structure with majority (> 90%) of Bi -2223( Bi 2 Sr 2 Ca 2 Cu 3 O 10) phase (c-lattice parameter ~ 36 Å). The proportion of Bi -2223 phase decreases slightly with an increase in x. The lattice parameters a and c of main phase ( Bi -2223) do not change significantly with increasing x. Superconducting critical transition temperature (Tc) decreases with x as evidenced by both resistivity [ρ(T)] and ac magnetic susceptibility [χ(T)] measurements. Interestingly the decrement of Tc is not monotonic and the same saturates at around 96 K for x > 0.06. In fact Tc decreases fast (~ 10 K/at%) for x = 0.015 and 0.03 samples and later nearly saturates for higher x values. Present results of Zn doping in Bi -2223 system are compared with other Zn -doped HTSC (high temperature superconducting) systems, namely the RE -123 ( REBa 2 Cu 3 O 7) and La -214 (( La, Sr )2 CuO 4).

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