Dresden 2006 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 9: Transport: Nanoelectronics III - Molecular Electronics

TT 9.13: Vortrag

Montag, 27. März 2006, 17:15–17:30, HSZ 304

Kondo effect in molecular magnets — •Christian Romeike, Maarten R. Wegewijs, Walter Hofstetter, and Herbert Schoeller — ITP A, RWTH Aachen

Motivated by recent experiments by Heersche et al. [1] we investigate linear transport through a single molecular magnet (SMM) in the regime of strong coupling to the electrodes. The molecule is modeled by a spin Hamiltonian incorporating the generic properties of a SMM: an easy-axis anisotropy, an easy-plane anisotropy perturbation leading to the quantum tunneling of magnetic moment (QTM) and a large spin ( S >1/2). Using a scaling analyses and the numerical renormalization group we find that for half-integer spin S the molecule acts as an anisotropic, effective pseudo-spin 1/2 Kondo-impurity of which electrons can resonantly scatter. Electron- and spin-tunneling processes cooperate to produce a quantum tunneling of the magnetization (QTM) (which is forbidden by time-reversal symmetry for isolated SMMs with half-integer S) and a zero-bias anomaly in conductance. The Kondo temperature is found to depend sensitively on the ratio of the easy-plane and easy-axis anisotropies in a non-monotonic way. We discuss criteria for candidate SMMs for transport experiments.

[1] H. Heersche et al., cond-mat/0510732