Determination of pressure properties of superconducting systems based on characteristic ratios 2\u0394(0)/Tc and \u0394C(Tc)/CN(Tc)

Mateusz Krzyzosiak,Adam Gonczarek,Lucjan Jacak,Ryszard Gonczarek

doi:10.1038/s41598-018-36733-1

Mateusz Krzyzosiak, Adam Gonczarek + Show 2 more

Open Access

https://doi.org/10.1038/s41598-018-36733-1

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Abstract

A simplified analytical model of the effect of high pressure on the critical temperature and other thermodynamic properties of superconducting systems is developed using the general conformal transformation method and group-theoretical arguments. Relationships between the characteristic ratios { {mathcal R} }_{1}equiv 2{rm{Delta }}(0)/{T}_{{rm{c}}} and { {mathcal R} }_{2}equiv {rm{Delta }}C({T}_{{rm{c}}})/{C}_{{rm{N}}}({T}_{{rm{c}}}) and the stability of the superconducting state is discussed. Including a single two-parameter fluctuation in the density of states, placed away from the Fermi level, stable solutions determined by { {mathcal R} }_{1} are found. It is shown that the critical temperature Tc(p), as a function of high external pressure, can be predicted from experimental data, based on the values of the two characteristic ratios, the critical temperature, and a pressure coefficient measured at zero pressure. The model can be applied to s-wave low-temperature and high-temperature superconductors, as well as to some novel superconducting systems of the new generation. The problem of emergence of superconductivity under high pressure is explained as well. The discussion is illustrated by using experimental data for superconducting elements available in the literature. A criterion for compatibility of experimental data is formulated, allowing one to identify incompatible measurement data for superconducting systems for which the maximum or the minimum critical temperature is achieved under high pressure.

Highlights

Recent discoveries of new classes of superconducting materials, with the most prominent example of iron-based superconductors, and ongoing development of superconductivity-based devices in the fields such as quantum information processing and fast digital circuits have kept superconductivity in the spotlight on the condensed matter physics stage
In refs12,13 we developed a simple analytical model of the effect of high pressure on the critical temperature and other thermodynamic properties of superconductors
In our previous work33, we have identified and discussed four universal types of the response of superconducting systems to an external high pressure, in terms of the dependence of the critical temperature on pressure

Summary

Introduction

Recent discoveries of new classes of superconducting materials, with the most prominent example of iron-based superconductors, and ongoing development of superconductivity-based devices in the fields such as quantum information processing and fast digital circuits have kept superconductivity in the spotlight on the condensed matter physics stage. Many properties of novel superconducting systems under high external hydrostatic pressure have been recently studied by ab-initio numerical calculations. Many properties of novel superconducting systems under high external hydrostatic pressure have been recently studied by ab-initio numerical calculations1–11 The results of these studies are usually in quite a good agreement of with the available experimental data. Being successful in providing quantitative characteristics of superconducting systems under high pressure, the ab-initio studies do not provide much information about which of the system’s parameters and to what extent affect these characteristics and material properties. Different experimental techniques may provide different estimates for the same parameter These fluctuations are again usually of the order of a few percent. The numerical results given below, derived within the specified precision, should be treated as estimates and may be subject to minor changes, depending on the precision of the experimental data available

Methods

Conclusion