Jens Birch, Lars Hultman and Igor Abrikosov (Linköping)
Ilia Katardjiev (Uppsala)
External Partners
Björgvin Hjörvarsson (Uppsala University)
Scientific Objectives
Theoretical studies: identification of potential material candidates, modeling of ion-surface interactions and gas-phase collisions during magnetron sputtering.
Magnetron sputtering of Pt/Co multilayer structures using a high flux of assisting low energy ions. Characterizations using primarily X-ray reflectivity, diffraction and diffuse scattering.
Technology Transfer Objectives
Patent/IPR of expected discoveries of tailored multilayers, not only optical but also semiconducting and magnetic for all possible applications.
Collaboration with company and an associated EU-project
Research plan:
Production of reflective optics for instrumentation in the X-ray wavelength region. Because of the low interacting nature of X-ray radiation, so called multilayer structures, where the individual layer thicknesses are only a few atoms (~0.4-5 nm) must be used. Deposition of smooth and abrupt interfaces need to be developed to fulfil the strict requirements.
The multilayer structures will be synthesized using magnetron sputtering, and the effect of different growth parameters will be analyzed primarily using X-ray reflectivity, diffraction, and diffuse scattering, together with TEM studies.
The Pt/Co and Pt/Mg multilayer systems are candidates as optical elements for normal-reflection of the Fe XVII (1.7 nm wavelength) emission line. Research will in the beginning consist of analytical studies to further identify potential material candidates, and statistical modeling of the ion-surface interaction and gas-phase collisions. A common growth window for these materials does not exist today, and a modification and development of the existing and unique deposition method is required.
The deposition technique with a high flux of low energy ion assistance have shown indications of producing amorphous metals when deposited as sub-nm layers. This can be important for the realization of abrupt interfaces, but also for other physical properties. To stabilize an amorphous structure also impurities can be introduced to assist preventing nucleation of crystallites. The concentration of impurities can be determined using elastic recoil detection analysis (ERDA). Simulations of nucleation processes will be carried out using MD-calculations.
High temperature stability of multilayers will be studied using in-situ X-ray reflectivity and diffraction under heat treatment up to 1400 ºC. To study the reflectivity performance of the multilayers at the intended X-ray wavelength, absolute reflectivity and diffuse X-ray scattering will be measured at the synchrotron radiation facility BESSY.
