Molecular quantum spintronics using single-molecule magnets

Moderation: Prof. Dr. Wolfgang Kuch, Freie Universität Berlin

Berliner Physikalisches Kolloquium
im Magnus-Haus, Am Kupfergraben 7, 10117 Berlin
Eine gemeinsame Veranstaltung der Physikalischen Gesellschaft zu Berlin e.V. (PGzB),
der Freien Universität Berlin (FUB), der Humboldt-Universität zu Berlin (HUB),
der Technischen Universität Berlin (TUB) und der Universität Potsdam (UP),
gefördert durch die Wilhelm und Else Heraeus-Stiftung.

Zusammenfassung
The field called molecular quantum spintronics combines the concepts of spintronics, molecular electronics and quantum computing. Various research groups are currently developing low-temperature scanning tunnelling microscopes to manipulate spins in single molecules, while others are working on molecular devices to read and manipulate the spin state and perform basic quantum operations. We will discuss this still largely unexplored field and present our first results. For example, we have built a novel spin-valve device in which a non-magnetic molecular quantum dot, consisting of a single-wall carbon nanotube contacted with non-magnetic electrodes, is laterally coupled to a TbPc2 molecular magnet. The localized magnetic moment of the single molecule magnet (SMM) led to a magnetic field-dependent modulation of the conductance in the nanotube with magnetoresistance ratios of up to 300% below 1 K. Using a molecular spin-transistor, we achieved the electronic read-out of the nuclear spin of an individual metal atom embedded in an SMM. We could show very long spin lifetimes (> 10 s). Using the hyperfine Stark effect, which transforms electric fields into local effective magnetic fields, we could not only tune the resonance frequency by several MHz, but also perform coherent quantum manipulations on a single nuclear qubit faster than a µs by means of electrical fields only, establishing the individual addressability of identical nuclear qubits.