M.Sc. topic: High-frequency EPR-spectroscopy on molecular magnets

Magnetic molecules are a new class of quantum magnets realizing zero-dimensional systems. They consist of a core with a finite number of magnetically strongly interacting paramagnetic ions. The anisotropy barrier induced by the magnetic core results in bistable ground state of magnetization at low temperature. Moreover, in case of a bistable ground state set, the famous quantum tunneling of the magnetization is observed, one of the very few macroscopic quantum effects in condensed matter. High-frequency ESR Spectroscopy is particularly devoted to investigate such metal-organic materials, i.e. spin state, spin dynamics, anisotropy and spin-orbit coupling, etc.

Within the thesis, students will:

• learn to measure at low-temperatur, to handle ultra-cold liquids, and to operate superconducting magnets withs fields up to 18 Tesla,
• operate a THz-ESR spectrometer,
• measure a metal-organic paramagnetic compound,
• analyse the results regarding the above-mentioned pyhsical properties.

Recent publications of the group in this field:

• Chemisorption of Exchange-Coupled [Ni2L(dppba)]+ Complexes on Gold via Ambidentate 4-(Diphenylphosphino)benzoate Coligands, M. Golecki et al., Chem. Eur. J. 19, 7787 – 7801 (2013), 2013
• New Dinuclear Nickel(II) Complexes: Synthesis, Structure, Electrochemical, and Magnetic Properties. D. Yakhvarov et al., Inorg. Chem. 50, 4553-4558 (2011), 2011
• A new family of 1D exchange biased heterometal single-molecule magnets: Observation of pronounced quantum tunneling steps in the hysteresis loops of quasi-linear {Mn₂Ni₃} clusters. A. Das et al., JACS 133 (2011) 3433-3443, 2011
• V. Miluykov et al., Ligand controlled magnetism of binuclear 1,2-diphosphacyclopentadienyl manganese(I) complexes, Organometallics 29, 1339-1342 (2010) URL
• Y. Krupskaya et al., Interplay of Magnetic Exchange Interactions and Ni-S-Ni Bond Angles in Polynuclear Nickel(II) Complexes. ChemPhysChem 11, 1961-1970 (2010) URL
• Y Krupskaya et al., High-Field ESR and Magnetization Study of a Novel Macrocyclic Chelate Trinuclear Ni(II) Complex. J Low Temp Phys 159, 84-87 (2010) URL