Giant magnetic proximity effect in amorphous layered magnets

Abstract

Here we study the magnetic proximity effect in amorphous layered magnets of alternating high- and low-${T}_{\text{c}}$ materials using magnetometry and polarized neutron reflectivity. By altering the thickness of either the high- or low-${T}_{\text{c}}$ layer we are able to extract the induced magnetic moment in the low-${T}_{\text{c}}$ layer directly and study how it scales with thickness. We observe that the ordering temperature of the low-${T}_{\text{c}}$ layer is enhanced and above which a second magnetically ordered state with a very large extension is observed. This induced magnetic state survives to a temperature at least three times that of the ordering temperature of the low-${T}_{\text{c}}$ layer and the induced magnetization is approximately constant throughout at least a 10-nm-thick layer. The induced magnetic region within the low-${T}_{\text{c}}$ layer does not depend on the thickness of the adjacent high-${T}_{\text{c}}$ layer.