Reversible magnetic switching of high-spin molecules on a giant Rashba surface. Issue 1 (December 2018)

• Record Type: Journal Article
• Authors: Kügel, Jens; Karolak, Michael; Krönlein, Andreas; Serrate, David; Bode, Matthias; Sangiovanni, Giorgio
• Is Part Of: Npj quantum materials. Volume 3:Issue 1(2018)
• Page Start: 1
• Page End: 7
• Publication Date: 2018-12
• Subjects: Superconductors -- Periodicals; Quantum theory -- Periodicals; 530.12
• DOI: 10.1038/s41535-018-0126-z
• Languages: English
• ISSNs: 2397-4648

Abstract

Abstract The quantum mechanical screening of a spin via conduction electrons depends sensitively on the environment seen by the magnetic impurity. A high degree of responsiveness can be obtained with metal complexes, as the embedding of a metal ion into an organic molecule prevents intercalation or alloying and allows for a good control by an appropriate choice of the ligands. There are therefore hopes to reach an "on demand" control of the spin state of single molecules adsorbed on substrates. Hitherto one route was to rely on "switchable" molecules with intrinsic bistabilities triggered by external stimuli, such as temperature or light, or on the controlled dosing of chemicals to form reversible bonds. However, these methods constrain the functionality to switchable molecules or depend on access to atoms or molecules. Here, we present a way to induce bistability also in a planar molecule by making use of the environment. We found that the particular "habitat" offered by an antiphase boundary of the Rashba system BiAg2 stabilizes a second structure for manganese phthalocyanine molecules, in which the central Mn ion moves out of the molecular plane. This corresponds to the formation of a large magnetic moment and a concomitant change of the ground state with respect to the conventional adsorption site. The reversible spin switch found here shows how we can not only rearrange electronic levels or lift orbital degeneracies via the substrate, but even sway the effects of many-body interactions in single molecules by acting on their surrounding. Molecular Spintronics: Switchable spin states in a planar molecule A new structure is stabilized by positioning MnPc molecule on top of an antiphase boundary of BiAg2 surface alloy, which lead to switchable spin states by electric field. An international team led by Jens Kügel from Universität Würzburg study the stable structures of MnPc on reconstructed surface alloy of Bi on Ag(111) (BiAg2 ). They find that a new stable structure, where Mn protrudes out of the molecular plane, is stabilized when MnPc is positioned on top of an antiphase boundary of BiAg2 . The new structure has a high magnetic moment, which can be switchable to the lower moment planar structure by an applied electric field from an STM tip. The results provide possible new paths to molecular electronics by controlling the environment rather than the molecule itself.