Influence of the interface local chemistry on the magnetic anisotropy of (Fe/Dy) multilayers

(Fe 3 nm/Dy 2 nm) multilayers deposited at 300 and 600 K have been investigated by SQUID magnetometry. These samples were deposited by thermal evaporation under ultra-high vacuum on (1 1 1) Si substrates. Their magnetic hysteresis loops show that the magnetic properties strongly depend on the deposition temperature, since the perpendicular magnetic anisotropy is much higher for the sample prepared at 600 K. In order to understand this phenomenon, a fine investigation of the structure and chemistry of the interfaces has to be carried out. As a first step, a (Dy/Fe) multilayer has been deposited on a preformed tungsten tip and analysed by tomographic atom probe (TAP). A three-dimensional reconstruction of the layers has been obtained that enabled the interfaces between iron and dysprosium to be observed at the atomic scale.