Understanding the magnetoresistance of a ferromagnetic metal-semiconductor bilayer

Spintronic devices using insulating materials offer new advantages for low-power information technologies. A potential material for such proof-of-principle devices is ferromagnetic EuS, which in contact with conducting ferromagnetic permalloy (Py) exhibits an intriguing multi-level magnetoresistance. There is evidence to suggest that this effect originates from a non-collinear alignment of the magnetisation in the two ferromagnetic layers. To obtain insight to the magnetoelectric behaviour and to find potential pathways for device optimisation, we aim to use polarised neutron reflectometry with polarisation analysis to determine the in-plane canting angle between the magnetisation in the EuS and the Py layers. By measuring this canting we can obtain coupling constants that further describe the complex longitudinal and transverse magnetoresistive response we observe in EuS|Py devices.