Characteristics of the Eliashberg Formalism on the Example of High-Pressure Superconducting State in Phosphor |

A.M. Duda
^{a}, R. Szczęśniak^{a,b}, M.A. Sowińska^{a} and I.A. Domagalska^{a}Institute of Physics, Częstochowa University of Technology, al. Armii Krajowej 19, 42-200 Częstochowa, Poland
^{b}Institute of Physics, Jan Długosz University in Częstochowa, al. Armii Krajowej 13/15, 42-200 Częstochowa, Poland |

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The work describes the properties of the high-pressure superconducting state in phosphor: p ∈ {20, 30, 40, 70} GPa. The calculations were performed in the framework of the Eliashberg formalism, which is the natural generalization of the BCS theory. The exceptional attention was paid to the accurate presentation of the used analysis scheme. With respect to the superconducting state in phosphor it was shown that the observed not-high values of the critical temperature ([T_{C}]_{p=30}^{max} = 8.45 K) result not only from the low values of the electron-phonon coupling constant, but also from the very strong depairing Coulomb interactions. Additionally the inconsiderable strong-coupling and retardation effects force the dimensionless ratios R_{Δ}, R_{C}, and R_{H} - related to the critical temperature, the order parameter, the specific heat, and the thermodynamic critical field - to take the values close to the BCS predictions. |

DOI: 10.12693/APhysPolA.130.641 PACS numbers: 74.20.Fg, 74.25.Bt, 74.62.Fj |