Cooper pair trajectories in superconducting slab at self-field conditions

TL;DR

This paper investigates the trajectories of charge carriers in a superconductor slab under self-field conditions, revealing non-intuitive meander paths and potential mechanisms for power dissipation.

Contribution

It provides a novel calculation of charge carrier trajectories showing they are not rectilinear but meander-shaped, affecting magnetic flux and dissipation.

Findings

Charge carriers follow meander trajectories crossing the slab thickness.

Particles with low velocity can move opposite to the current.

Disturbance in flux distribution may cause power dissipation.

Abstract

Dissipative-free electric current flow is one of the most fascinating and practically important property of superconductors. Theoretical consideration of the charge carriers flow in infinitely long rectangular slab of superconductor in the absence of external magnetic field (so called, self-field) is based on an assumption that the charge carriers have rectilinear trajectories in the direction of the current flow whereas the current density and magnetic flux density are decaying towards superconducting slab with London penetration depth as characteristic length. Here, we calculate charge particle trajectories (as single electron/hole, as Cooper pair) at self-field conditions and find that charge carriers do not follow intuitive rectilinear trajectories along the slab surface, but instead ones have meander shape trajectories which cross the whole thickness of the slab. Moreover, if the particle velocity is below some value, the charge moves in opposite direction to nominal current flow. This disturbance of the canonical magnetic flux density distribution and backward movement of Cooper pairs can be entire mechanism for power dissipation in superconductors.