Penetration depth of Cooper pairs in the IrMn antiferromagnet

TL;DR

This study investigates how Cooper pairs penetrate the IrMn antiferromagnet by examining the recovery of superconductivity in heterostructures, providing new experimental insights into the characteristic length scale of Cooper pair penetration in antiferromagnets.

Contribution

The paper presents experimental determination of the Cooper pair penetration depth in IrMn antiferromagnets through superconductivity recovery measurements in heterostructures.

Findings

Up to 10% recovery of superconducting critical temperature observed.

Characteristic length for Cooper pair penetration in IrMn deduced from spacer thickness dependence.

Experimental access to Cooper pair penetration depth in antiferromagnets achieved.

Abstract

Suppression of superconductivity due to the proximity effect between a superconductor and a ferromagnet can be partially alleviated when a Cooper pair simultaneously samples different directions of the short-range exchange field. The superconductor's critical temperature, TC, is therefore expected to partially recover when the ferromagnet is in a multi-domain state, as opposed to a single-domain state. Here, we discuss series of experiments performed with ferromagnet(Pt/Co)/spacer(IrMn and Pt)/superconductor(NbN) heterostructures. By tuning the various parameters in play, e.g., superconducting coherence length-to-thicknesses ratio, and domain sizes, we obtained up to 10 percent recovery of the superconducting critical temperature {\Delta}TC/TC. This large-scale recovery made novel investigations possible. In particular, from the spacer thickness-dependence of {\Delta}TC/TC, it was possible to deduce the characteristic length for Cooper pair penetration in an IrMn antiferromagnet. This information is crucial for electronic transport, and up to now has been difficult to access experimentally for antiferromagnets.