5 research outputs found
Superconductivity of calcium under the pressure at 120 GPa
The properties of the superconducting state in calcium under the pressure at
120 GPa were analyzed. By using the imaginary axis Eliashberg equations it has
been shown, that the Coulomb pseudopotential reaches the high value equal to
0.215. In the considered case, the critical temperature is not properly
described by the Allen-Dynes formula and it should be calculated with an use of
the modified expression. In the paper the exact solutions of the Eliashberg
equations on the real axis were also obtained. On this basis it was stated,
that the effective potential of the electron-electron interaction is attractive
for the frequencies lower or equal to the maximum phonon frequency. Then, the
dimensionless parameter 2\Delta(0)/k_{B}T_{C}=4.10 was calculated. In the last
step it has been proven, that the ratio of the electron effective mass to the
bare electron mass is high and reaches its maximum equal to 2.36 for the
critical temperature
The superconducting phase of Calcium under the pressure at 200 GPa: the strong-coupling description
The thermodynamic parameters of the superconducting state in Calcium under
the pressure at 200 GPa have been determined. The numerical analysis by using
the Eliashberg equations in the mixed representation has been conducted. It has
been stated, that the critical temperature () decreases from 36.15 K to
20.79 K dependently on the assumed value of the Coulomb pseudopotential
(). Next, the order parameter near the temperature of zero
Kelvin () has been obtained. It has been proven, that the
dimensionless ratio decreases from 4.25 to 3.90
together with the growth of . Finally, the ratio of the electron
effective mass to the electron bare mass () has been
calculated. It has been shown, that takes the high value in
the whole range of the superconducting phase's existence, and its maximum is
equal to 2.23 for T=T_{C}.Comment: 5 pages, 5 figure
Scalability of non-adiabatic effects in lithium-decorated graphene superconductor
The analysis is conducted to unveil how the non-adiabatic effects scale within the superconducting phase of lithium-decorated graphene . Based on the Eliashberg formalism it is shown that the non-adiabatic effects notably reduce essential superconducting parameters in and arise as a significant oppressor of the discussed phase. Moreover, non-adiabaticity is found to scale with the strength of superconductivity, proportionally to the phonon energy scale and inversely with respect to the electron-phonon coupling. These findings are partially in contrast to other theoretical studies and show that superconductivity in is more peculiar than previously anticipated. In this context, the guidelines for enhancing superconducting phase in and sibling materials are also proposed