Exploring novel current-driven magnetization reversal using polarised neutron reflectometry

This experiment will clarify the novel field-free current-driven magnetization switching we have recently observed in ferromagnet/heavy metal (FM/HM) ultra-thin film bilayers. We will detect the influence of the spin-orbit torque on the interface magnetization in a model device structure; a long thin bilayer wire allowing the high current density for spin-orbit torque switching whilst also providing scattering volume for detection of a small magnetic signal using polarised neutron reflectivity. PNR will distinguish between plausible current-induced magnetization configurations; a novel current-driven reversal occurs within a thin region close to either the FM/HM or substrate/FM interface, producing a twisted `exchange-spring' state. These measurements will demonstrate the capabilities of PNR to determine functional information from model device structures.