Regensburg 2019 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 47: Quantum Magnets, Molecular Magnets and Skyrmions
TT 47.3: Talk
Wednesday, April 3, 2019, 15:30–15:45, H23
HF-EPR study on the exchange couplings in 3d-4f heterometallic complexes — •Changhyun Koo1, Arne Bahr1, Sebastian Schmidt2, Yan Peng2, Ahmed Naushad3, Maheswaran Shanmugam3, Annie K. Powell2, and Rüdiger Klingeler1,4 — 1Kirchhoff Institute for Physics, Heidelberg University, Heidelberg, Germany — 2Institute of Inorganic Chemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany — 3Department of Chemistry, Indian Institute of Technology, Mumbai, India — 4Center for Advanced Materials, Heidelberg University, Heidelberg, Germany
3d-4f heterometallic complexes are suggested to enhance the magnetic anisotropy barrier in metal-organic coordination complexes. Though magnetic exchange coupling between 3d and 4f ions is essential, its quantitative determination by conventional magnetometry remains challenging. Our high-frequency electron paramagnetic resonance (HF-EPR) studies enable to determine the precise values of 3d-4f exchange interaction (J3d−4f) as well as anisotropy of the 3d-ions. The EPR data, analyzed in terms of a Hamiltonian involving the Ising-spin concept for Ln ions, enable to derive information on the ground state and J3d−4f in the complexes. The results on several series of complexes, i.e., [Fe4IIILn2III(Htea)4(µ-N3)4(N3)3(piv)3], [Ni2IILn2III(CH3CO2)3(HL)4(H2O)2](NO3)3 (Ln = Tb, Dy, Ho, Yb, and Gd), and [Co2IIDy2III(L)4(NO3)2X (X = (MeOH)2 and (DMF)2]) will be presented and general conclusions about magneto-structural correlations will be drawn which suggest routes to optimizing ferromagnetic J3d−4f.