Modification of magnetic fluctuations by interfacial interactions in artificially engineered heavy-fermion superlattices

TL;DR

This study investigates how interfacial interactions in engineered heavy-fermion superlattices modify magnetic fluctuations, revealing suppression or enhancement depending on the neighboring layer, using nuclear magnetic resonance measurements.

Contribution

It demonstrates that interfacial interactions can significantly alter magnetic properties in heavy-fermion superlattices, providing new insights into magnetic control at interfaces.

Findings

Magnetic fluctuations weaken in CeCoIn5/YbCoIn5 superlattices due to Rashba spin-orbit effect.

Magnetic fluctuations are anomalously enhanced in CeCoIn5/CeRhIn5 superlattices below 6 K.

Interfacial interactions can be used to modify magnetic properties in engineered superlattices.

Abstract

Recent progress in the fabrication techniques of superlattices (SLs) has made it possible to sandwich several-layer-thick block layers (BLs) of heavy-fermion superconductor CeCoIn5 between conventional-metal YbCoIn5 BLs or spin-density-wave-metal CeRhIn5 BLs of a similar thickness. However, the magnetic state in each BL, particularly at the interface, is not yet understood, as experimental techniques applicable to the SL system are limited. Here, we report measurements of 59Co nuclear magnetic resonance, which is a microscopic probe of the magnetic properties inside the target BLs. In the CeCoIn5/YbCoIn5 SL, the low-temperature magnetic fluctuations of the CeCoIn5 BL are weakened as expected from the Rashba spin-orbit effect. However, in the CeCoIn5/CeRhIn5 SL, the fluctuations show an anomalous enhancement below 6 K, highlighting the importance of the magnetic proximity effect occurring near a magnetic-ordering temperature TN ~ 3 K of the CeRhIn5 BL. We suggest that the magnetic properties of the BLs can be altered by the interfacial interaction, which is an alternative route to modify the magnetic properties.