Introduction of Zr in nanometric periodic Mg/Co multilayers
  We study the introduction of a third material, namely Zr, within a nanometric periodic Mg/Co structure designed to work as optical component in the extreme UV (EUV) spectral range. Mg/Co, Mg/Zr/Co, Mg/Co/Zr and Mg/Zr/Co/Zr multilayers are designed, then characterized in terms of structural quality and optical performances through X-ray and EUV reflectometry measurements respectively. For the Mg/Co/Zr structure, the reflectance value is equal to 50% at 25.1 nm and 45deg of grazing incidence and reaches 51.3% upon annealing at 200deg C. Measured EUV reflectivity values of tri-layered systems are discussed in terms of material order within a period and compared to the predictions of the theoretical model of Larruquert. Possible applications are pointed out. 
K. Le Guen (LCP-MR), M.-H. Hu (LCP-MR), J.-M. Andr\'e (LCP-MR),   Philippe Jonnard (LCP-MR), S.-K. Zhou (IPOE), H.-C. Li (IP...
cond-mat.mtrl-sci cond-mat.other physics.optics