Hydrogenation of superconducting cuprate thin films studied by neutron reflectometry

Hydrogenation of thin films allows for targeted and in many cases reversible modification of their structural, electronic, and magnetic properties. In the case of the cuprates, hydrogen doping offers an additional degree of freedom to access the rich phase diagram [4], and specifically to tune the superconducting transition temperature Tc. The aim of the experiment is to understand the incorporation mechanism and the hydrogen-induced effects. Essential for understanding the hydrogen-incuced effects is the depth resolved measurement the H concentration in the layers and at the interfaces. Neutron reflectometry is the only method providing these data in direct and non-destructive way, in contrast to x-ray reflectometry, which is not sensitive to hydrogen and and sees only indirect effects of hydrogenation, such as lattice expansion and layer swelling.