This experiment will continue our recent successful experiments on XMaS, aiming to clarify the novel current-driven magnetization switching which we have recently observed in CoFeTaB/Pt ultra-thin film bilayers, where the magnetization in CoFeTaB appears to twist into a stable nanometer-scale 'exchange-spring' configuration close to the interface. We will detect the proximity induced magnetization in Pt, which arises close to the interface with ferromagnetic CoFeTaB, using the element-specificity of resonant x-ray magnetic scattering, and use this to track the interface magnetization in CoFeTaB during field- and current-driven magnetization reversal. This will enable us to unambiguously determine how the current drives energy-efficient interfacial magnetization reversal in this system. We will also begin to look at Ta within the CoFeTaB layer; the distribution of Ta modifies local exchange interaction, and may explain how the exchange-spring state is able to form in such a thin film.