T. Slezak

An ultrahigh vacuum system for in situ studies of thin films and nanostructures by nuclear resonance scattering of synchrotron radiation.

A multifunctional ultrahigh vacuum (UHV) system has been set up at the nuclear resonance beamline ID18 of the European Synchrotron Radiation Facility (ESRF). Thin and ultrathin films, nanoislands and -wires, multilayers, and stoichiometric oxides can be prepared by molecular beam epitaxy and characterized by low-energy electron diffraction, Auger electron spectroscopy, and reflection high-energy electron diffraction. Upon characterization the sample is transferred under UHV conditions to the chamber for experiments with the synchrotron beam. Electronic and magnetic properties, vibrational dynamics, and diffusion phenomena can be investigated by several synchrotron radiation based techniques, such as nuclear forward scattering, nuclear inelastic and quasielastic scattering, synchrotron radiation based perturbed angular correlations, and nuclear and electronic reflectivity. In addition, two portable UHV chambers serve to transfer the sample to other beamlines profiting from the available experimental techniques at the ESRF.

Probing the magnetic state of Fe/FeO/Fe trilayers by multiple isotopic sensor layers

To obtain depth-selected information in magnetic multilayers, we propose a measurement scheme based on nuclear resonant scattering from multiple isotopic sensor layers. It takes advantage of the depth dependence of the photon wavefield intensity in grazing incidence geometry to enhance the signal from a given part of a multilayer. The technique is applied to study the magnetic structure of a Fe/Fe-oxide/Fe trilayer. We are able to fully determine in a direct manner the magnetic state of two ultrathin F57e probe layers embedded in the system. The proposed technique can potentially be extended to various grazing incidence x-ray scattering methods.

Diffusion of muons in metallic multilayers

The development of the low energy muon beam at PSI opens the possibility of studying muon diffusion in artificially layered structures within the nm scale. Here, we report on first muon diffusion experiments on different Cr=x nm Au=Cr trilayers ðx ¼ 19; 21; 30; 39Þ in the temperature range from 5 to 320 K: If the appropriate implantation energy is chosen, the initial muon implantation profile is centered within the non-magnetic Au layer. Muons stopping in magnetic Cr or penetrating the Au/Cr interface by thermally activated diffusion immediately lose their spin polarization. The depolarization of the LE-mSR signal allows extraction of the time-dependent fraction of muons reaching one of the interfaces. r 2002 Elsevier Science B.V. All rights reserved.