Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 28: Postersitzung (Elektronische Struktur, Grenzfläche fest-flüssig, Halbleiteroberflächen und -grenzflächen, Magnetismus und Symposium SYXM, Methodisches, Nanostrukturen, Oberflächenreaktionen, Teilchen und Cluster, Zeitaufgelöste Spektroskopie)

O 28.86: Poster

Mittwoch, 10. März 2004, 16:00–19:00, Bereich C

Inducing spin crossover in metallo-supramolecular polyelectrolytes through an amphiphilic phase transition — •Yves Bodenthin1, U. Pietsch1, D. Kurth2, and H. Möhwald21University of Potsdam, Institute of Physics, Am Neuen Palais 10, 14469 Potsdam, Germany — 2MPI-KG Golm, Am Mühlenberg 1, 14476 Potsdam-Golm

In the last years resonant magnetic X-ray reflectivity experiments (XMCD) become important for the investigation of molecular magnetism in thin films.

In the present work we report a novel approach to affect spin crossover by introducing mechanical strain through an amphiphilic phase transition in a metallo-supramolecular polyelectrolyte-amphiphile complex (PAC). The investigated system consists of thin layers deposited in Y-conformation on a silicon substrate by means of Langmuir-Blodgett technique.

It was observed by EXAFS, x-ray reflectivity and in-plane diffraction experiments that the structural phase transition in the amphiphilic mesophase is responsible for the distortion of the coordination geometry of the tightly coupled transition metal centres. Consequently, the energetic separation of the subsets of the iron d-orbitals changes and gives rise to spin crossover. Using temperature resolved SQUID and XMCD measurements we observe a diamagnetic to paramagnetic phase transition above room temperature which is connected to a structural phase transition between two liquid crystalline phases.

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