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MA: Fachverband Magnetismus

MA 28: Cooperative Phenomena: Spin Structures and Magnetic Phase Transitions

MA 28.9: Vortrag

Mittwoch, 19. März 2025, 17:15–17:30, H19

Investigating the soft X-ray-induced spin-state switching in the room temperature regime of a Fe(II) spin-crossover complex — •Lea Kämmerer¹, Carolin Schmitz-Antoniak^2,3, Tobias Lojewski¹, Damian Günzing¹, Torsten Kachel⁴, Florin Radu⁴, Radu Abrudan⁴, Katharina Ollefs¹, Senthil K. Kuppusamy⁵, Mario Ruben^5,6, and Heiko Wende¹ — ¹University of Duisburg-Essen and CENIDE — ²Forschungszentrum Jülich — ³University of Applied Sciences Wildau, — ⁴Helmholtz-Zentrum Berlin — ⁵Karlsruhe Institute for Technology — ⁶Institut de Science et d’Ingénierie Supramoléculaires

Spin-crossover complexes exhibit two distinct spin-states, designated as low-spin and high-spin, which are contingent upon the ligand field surrounding the central metal ion. It is possible to induce a switching of the spin state in these complexes through the use of soft X-rays. The complex Fe(1−bpp−COOC₂H₅)₂(BF₄)₂CH₃CN exhibits an abrupt spin-state switching with an open thermal hysteresis around room temperature. Static X-ray absorption spectroscopy was performed at the synchrotron BESSY II, which allows for the analysis of the two spin states at the Fe L_2,3 absorption edges due to the presence of different fine structures. We gained insight into the cooperative mechanism that occurs during the soft X-ray-induced spin-state switching at room temperature. It was observed that once the effect was initiated in a thin film, a chain reaction led to further switching, even in the absence of soft X-rays. We thank the Deutsche Forschungsgemeinschaft for their financial support of the SFB 1242.

Keywords: Spin-Crossover; X-ray absorption spectroscopy; XANES; SOXIESST