Correcting 100 years of misunderstanding: electric fields in superconductors, hole superconductivity, and the Meissner effect

TL;DR

This paper challenges conventional views by proposing that electrostatic fields exist inside superconductors, driven by charge expulsion and spin currents, with a new electrodynamic theory applicable to all superconductors.

Contribution

It introduces a novel London-like electrodynamic theory that incorporates electrostatic fields and spin currents, differing from traditional BCS-London theory.

Findings

Electrostatic fields exist inside superconductors due to charge expulsion.

A macroscopic spin current, the 'Spin Meissner effect', is predicted in the ground state.

The theory explains various experimental observations across different superconductors.

Abstract

From the outset of superconductivity research it was assumed that no electrostatic fields could exist inside superconductors, and this assumption was incorporated into conventional London electrodynamics. Yet the London brothers themselves initially (in 1935) had proposed an electrodynamic theory of superconductors that allowed for static electric fields in their interior, which they unfortunately discarded a year later. I argue that the Meissner effect in superconductors necessitates the existence of an electrostatic field in their interior, originating in the expulsion of negative charge from the interior to the surface when a metal becomes superconducting. The theory of hole superconductivity predicts this physics, and associated with it a macroscopic spin current in the ground state of superconductors ("Spin Meissner effect"), qualitatively different from what is predicted by conventional BCS-London theory. A new London-like electrodynamic description of superconductors is proposed to describe this physics. Within this theory superconductivity is driven by lowering of quantum kinetic energy, the fact that the Coulomb repulsion strongly depends on the character of the charge carriers, namely whether electron- or hole-like, and the spin-orbit interaction. The electron-phonon interaction does not play a significant role, yet the existence of an isotope effect in many superconductors is easily understood. In the strong coupling regime the theory appears to favor local charge inhomogeneity. The theory is proposed to apply to all superconducting materials, from the elements to the high $T_c$ cuprates and pnictides, is highly falsifiable, and explains a wide variety of experimental observations.