Berlin 2012 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 16: Magnetic Particles / Clusters II

MA 16.7: Vortrag

Dienstag, 27. März 2012, 11:00–11:15, EB 202

Double exchange mediated ferromagnetic coupling between transition metal atoms in di-metal complexes — •Kalpataru Pradhan^1,2 and Purusottam Jena¹ — ¹Theoretical Physics III, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, D-86135 Augsburg, Germany — ²Physics Department, Virginia Commonwealth University, Richmond, VA 23284 USA

Recent discoveries of ferromagnetic ordering in mixed-valence di-metal [1] [2] complexes show that ferromagnetic double exchange in molecular magnets can indeed be achieved via charge disproportionation between valence-variable transition metal ions. Realization of the full technological potential of molecular magnets requires a fundamental understanding of the origin of magnetic coupling in molecular systems. Using gradient corrected density functional theory and Cl as a ligand we find that the magnetic coupling between transition metal atoms in a di-metal complex can be manipulated. Our calculations show that the ferromagnetic (FM) states of Co₂Cl₆ and Co₂Cl₇ are 0.07 eV and 0.20 eV lower in energy than their respective antiferromagnetic (AFM) states but they are nearly degenerate in Co₂Cl₈. The origin of ferromagnetic coupling is explained using the double exchange model caused by charge disproportionation.

B. Bechlars et al., Nat. Chem. 2, 362 (2010).

[2] Lin He and Lin Guo, Appl. Phys. Lett. 97, 182509 (2010).