Searching for high temperature superconductivity: From Mendeleev to Seiberg-Witten via Madelung and beyond

Abstract

Recently,a noticeable progress had been achieved in the area of high temperature superconductors. The maximum temperature of 250K for LaH(10) and 288K for CSH(8) were reported at the megabar pressures. The highest possible temperatures were achieved by employing hydrides of chemical elements. Empirically, many of these are made of Madelung-exceptional atoms. Here the theoretical background is provided explaining this observation. The, thus far empirical, Madelung rule is controlling Mendeleev's law of periodicity. Although the majority of elements do obey this rule, there are some exceptions. Thus, it is of interest to derive it and its exceptions theoretically in view of experimental findings. As a by product, such a study yields some plausible explanation of the role of Madelung-exceptional atoms in the design of hightemperature superconductors. Thus far the atoms obeying the Madelung rule and its exceptions were studied with help of the relativistic Hartree-Fock calculations. In this work we reobtain both the rule and the exceptions analytically. The newly developed methods are expected to be of value in quantum many-body theory and, in particular, in the theory of high temperature superconductivity. Ultimately, new methods involve some uses of the Seiberg-Witten (S-W) theory known as the extended Ginzburg-Landau theory of superconductivity. Using results of the S-W theory the difference between the Madelung-regular and Madelung-exceptional atoms is explained in terms of the topological transition. Extension of this, single atom, result to solids of respective elements is also discussed