# Entropy generation and momentum transfer in the superconductor-normal and normal-superconductor phase transformations and the consistency of the conventional theory of superconductivity

## TL;DR

This paper examines the thermodynamic consistency of the conventional theory of superconductivity during phase transitions, highlighting its inability to explain entropy and momentum transfer without contradictions, unlike the alternative hole superconductivity theory.

## Contribution

The paper critically analyzes the conventional theory of superconductivity, revealing its limitations in explaining entropy and momentum transfer during phase transitions, and contrasts it with the hole superconductivity theory.

## Key findings

- Conventional theory cannot account for entropy-free momentum transfer during transitions.
- The N-S transition involves entropy generation inconsistent with thermodynamics.
- Hole superconductivity theory avoids these thermodynamic inconsistencies.

## Abstract

Since the discovery of the Meissner effect the superconductor to normal (S-N) phase transition in the presence of a magnetic field is understood to be a first order phase transformation that is reversible under ideal conditions and obeys the laws of thermodynamics. The reverse (N-S) transition is the Meissner effect. This implies in particular that the kinetic energy of the supercurrent is not dissipated as Joule heat in the process where the superconductor becomes normal and the supercurrent stops. In this paper we analyze the entropy generation and the momentum transfer between the supercurrent and the body in the S-N transition and the N-S transition as described by the conventional theory of superconductivity. We find that it is impossible to explain the transition in a way that is consistent with the laws of thermodynamics unless the momentum transfer between the supercurrent and the body occurs with zero entropy generation, for which the conventional theory of superconductivity provides no mechanism. Instead, we point out that the alternative theory of hole superconductivity does not encounter such difficulties.