Mechanical Control of Spin States in Spin-1 Molecules and the Underscreened Kondo Effect

J. J. PARKS, A. R. CHAMPAGNE, T. A. COSTI, W. W. SHUM, A. N. PASUPATHY, E. NEUSCAMMAN, S. FLORES-TORRES, P. S. CORNAGLIA, A. A. ALIGIA, C. A. BALSEIRO, G. K.-L. CHAN, H. D. ABRUÑA, AND D. C. RALPH

SCIENCE

AMER ASSOC ADVANCEMENT SCIENCE

Año: 2010 vol. 328 p. 1370 - 1373

0036-8075

The ability to make electrical contact to single molecules creates opportunities to examinefundamental processes governing electron flow on the smallest possible length scales. We reportexperiments in which we controllably stretched individual cobalt complexes having spin S = 1,while simultaneously measuring current flow through the molecule. The molecule’s spin states andmagnetic anisotropy were manipulated in the absence of a magnetic field by modification ofthe molecular symmetry. This control enabled quantitative studies of the underscreened Kondoeffect, in which conduction electrons only partially compensate the molecular spin. Our findingsdemonstrate a mechanism of spin control in single-molecule devices and establish that theycan serve as model systems for making precision tests of correlated-electron theories.