Ferromagnetism in certain alloys consisting of magnetic and nonmagnetic species can be activated by the presence of chemical disorder. This phenomenon is linked to an increase in the number of nearest-neighbor magnetic atoms and local variations in the electronic band structure due to the existence of disorder sites. An approach to induce disorder is through exposure of the chemically ordered alloy to energetic ions; collision cascades formed by the ions knock atoms from their ordered sites and the concomitant vacancies are filled randomly via thermal diffusion of atoms at room temperature. The ordered structure thereby undergoes a transition into a metastable solid solution. Here we demonstrate the patterning of highly resolved magnetic structures by taking advantage of the large increase in the saturation magnetization of Fe60Al40 alloy triggered by subtle atomic displacements. The sigmoidal characteristic and sensitive dependence of the induced magnetization on the atomic displacements manifests a sub-50 nm patterning resolution. Patterning of magnetic regions in the form of stripes separated by ∼ 40 nm wide spacers was performed, wherein the magnet/spacer/magnet structure exhibits reprogrammable parallel (↑/spacer/↑) and antiparallel (↑/spacer/↓) magnetization configurations in zero field. Materials in which the magnetic behavior can be tuned via ion-induced phase transitions may allow the fabrication of novel spin-transport and memory devices using existing lateral patterning tools.

Cryst. Res. Technol. 341999 1 71-88Starting from the origin and the informational content of Kossel interferences excited by electron and synchrotron radiation beams selected examples of microstructural applications, such as the precision determination of lattice constants, the precision determination of crystallographic orientation of single grains, the determination of local stresses/strains and the determination of tetragonal distortions of cubic lattices including the description of a variety of methods for analysis are presented.Ausgehend vom Prinzip der Entstehung und des Informationsgehaltes von elektronenstrahl-bzw. synchrotronstrahlangeregten Kossel-Aufnahmen werden Auswertungsmethoden und Anwendungen im Mikrobereich, wie die Präzisionsgitterkonstantenbestimmung, die Einzelkorn-Orientierungsbestimmung, die Eigenspannungsanalyse sowie die Diagnose von Abweichungen von der kubischen Symmetrie an ausgewählten Beispielen beschrieben.

That from us as X‐ray Rotation‐Tilt Technique (XRT Method) designated procedure principle represents a world innovation and overcomes essential disadvantages of comparable diffraction techniques known up to now. Starting from the origin and the informational content of the XRT interferences a realization of a special equipment and selected examples of some first applications are presented.

A new application of the KOSSEL and the XRT (X-ray Rotation-Tilt) technique arises from local residual stress measurements in micro regions. Already in 1996/97, we started to conduct such investigations based on the KOSSEL method. Because of the high lateral resolution residual stresses of the third kind can be determined. Some further evaluation procedures are described.

In 1996, we performed the first measurements of residual stresses by using synchrotron excited KOSSEL diffraction (at the beamline L of the HASYLAB, Hamburg). Our first findings as well as the principle of the determination procedure for obtaining residual stresses from KOSSEL lines are presented. The KOSSEL technique is a very suitable method for fast measurements of local residual stresses in micron regions. Because of the high lateral resolution even residual stresses of third order (inhomogeneities of the stress state within a grain) can be proved and calculated.Im Jahre 1996 führten wir die ersten Eigenspannungsmessungen mittels synchrotronstrahlangeregter KOSSEL-Beugung (an Beamline L des HASYLAB, Hamburg) durch. Die ersten Ergebnisse und das Prinzip der Eigenspannungsbestimmung werden hiermit vorgestellt. Die KOSSEL-Technik eignet sich besonders für schnelle lokale Eigenspannungsanalysen in Mikrobereichen. Aufgrund der hohen lateralen Auflösung können sogar Eigenspannungen III. Art nachgewiesen und berechnet werden.