Cooling of electrons via superconducting tunnel junctions and their arrays exhibiting nodal lines

TL;DR

This paper theoretically investigates electron cooling using superconducting tunnel junctions with complex entropy structures due to nodal lines, including arrays with ferroelectric layers, highlighting their potential for efficient heat removal.

Contribution

It introduces a novel theoretical model of electron cooling employing superconducting junctions with nodal lines and ferroelectric layers, expanding understanding of entropy-driven cooling mechanisms.

Findings

Nodal lines cause divergent density of states, enhancing cooling potential.

Arrays of junctions with ferroelectric layers improve heat removal efficiency.

Theoretical analysis shows feasibility of entropy-based electron cooling.

Abstract

We study theoretically a process of cooling electrons using a superconducting tunnel junction with a $\pi$ phase difference and a usual insulator or a ferroelectric in-between, and an array of such junctions with ferroelectric layers in-between. These setups have a complex structure of entropy due to nodal lines, where the density of states can be divergent or larger than for a free electron gas at a chemical potential level. We consider a small current running from the bath of electrons through the setup, where electrons have to have higher entropy, and thus remove heat from the bath.