Structural, electrical and magnetic properties of reactively DC sputtered Cu and Ti thin films. Application to Cu/Ti neutron supermirrors for low spin-flip applications

•A Cu/Ti neutron supermirror was developed and optimized for high overall and low spin-dependent neutron reflectivities.•Control of the roughness growth allowed to achieve 90% reflectivity at the reflection edge (polarized and non-polarized).•The magnetization of this coating was reduced to a level between 30 and 50 times below that of NiMo/Ti supermirrors.•The spin-flip reflectivity of < 1.8 × 10−5 makes these neutron mirrors suitable for extremely low-spin-flip applications [56].