Coherent charge and magnetic ordering in Ho/Y superlattice revealed by element-selective x-ray scattering

TL;DR

This study uses element-specific x-ray scattering to reveal how charge and magnetic orderings in Ho/Y superlattices are coherently maintained across layers, highlighting a new charge density wave that supports magnetic chirality transfer.

Contribution

It demonstrates the existence of a chiral charge density wave in Ho/Y superlattices that helps preserve magnetic chirality coherence across non-magnetic layers, a novel insight.

Findings

Identification of a 16 Å charge density wave propagating through Ho and Y layers.

Evidence of a chiral charge density wave supporting magnetic chirality coherence.

No magnetic proximity effect detected in Y layers.

Abstract

Magnetic rare-earth / non-magnetic metal superlattices are well-known to display chiral spin helices in the rare-earth layers that propagate coherently across the non-magnetic layers. However, the underlying mechanism that preserves the magnetic phase and chirality coherence across the non-magnetic layers has remained elusive. In this Letter, we use resonant and element-specific x-ray scattering to evidence directly the formation of two fundamentally different long-range modulations in a Holmium/Yttrium (Ho/Y) multilayer: the known Ho chiral spin helix with periodicity 25 {\AA}, and a newly observed charge density wave with periodicity 16 {\AA} that propagates through both the Ho and non-magnetic Y layer. With x-ray circular magnetic dichroism measurements ruling out the existence of a magnetic proximity effect induced moment in the non-magnetic Y layers, we propose that the charge density wave is also chiral, thus providing the means for the transmittance of magnetic chirality coherence between Ho layers.