Regensburg 2016 – scientific programme
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MA: Fachverband Magnetismus
MA 4: Bio- und molekularer Magnetismus
MA 4.7: Talk
Monday, March 7, 2016, 11:15–11:30, H33
Investigation of Ni2-complexes with Different Radical Bridges by High-Frequency Electron Spin Resonance — •Msia Tavhelidse1, Cebrail Pür1, Roland Bischoff2, Manuel Reh2, Hans-Jörg Krüger2, Changhyun Koo1, and Rüdiger Klingeler1 — 1Kirchhoff Institute of Physics, Heidelberg University, Heidelberg, Germany. — 2Department of Chemistry, University of Kaiserslautern, Kaiserslautern, Germany.
Magnetic properties of two Ni2 complexes, i.e. [ {Ni(L-N4Me2 )}2 (bpym*−} ] (CIO4 )3 (I) and [ {Ni(L-N4Me2 )}2 (µ-bptz) ] (CIO4 )3 (II), with different radical bridges are investigated by means of high-frequency electron spin resonance (HF-ESR) studies. In both complexes, Ni2+ ions (S = 1) are ferromagnetically coupled through a radical bridge with an unpaired electron. The high-spin S = 5/2 ground state is confirmed by the HF-ESR spectra which exhibit five almost equally separated resonance features. The frequency dependence of the resonances enables reading off significant zero-field-splitting (ZFS) for complexes. Temperature and frequency dependence of the spectra is analysed by means of exact diagonalization of the corresponding spin Hamiltonians. Best simulations of the experimental data unambiguously yields g-factors and anisotropy parameters of both complexes: gz=2.12, D=-1.15 K, and B40=-1.44·10−4 K for complex I, and gz=2.07, D=-1.58 K, and B40=-2.88·10−4 K for complex II. Spectral weight shift as a function of the temperature supports the best simulation parameters.