AVS 60th International Symposium and Exhibition
    Graphene and Other 2D Materials Focus Topic Tuesday Sessions
       Session GR+AS+EM+MI+MN-TuM

Paper GR+AS+EM+MI+MN-TuM1
Long-range Magnetic Order in a Purely Organic 2D Layer Adsorbed on Epitaxial Graphene

Tuesday, October 29, 2013, 8:00 am, Room 104 B

Session: Optical, Magnetic, Mechanical and Thermal Properties of 2D Materials
Presenter: A.L. Vazquez-de-Parga, Universidad Autónoma de Madrid, Spain
Authors: M. Garnica, Universidad Autónoma de Madrid, Spain
D. Stradi, Universidad Autónoma de Madrid, Spain
S. Barja, Universidad Autónoma de Madrid, Spain
F. Calleja, Universidad Autónoma de Madrid, Spain
C. Diaz, Universidad Autónoma de Madrid, Spain
M. Alcami, Universidad Autónoma de Madrid, Spain
N. Martin, Universidad Autónoma de Madrid, Spain
A.L. Vazquez-de-Parga, Universidad Autónoma de Madrid, Spain
F. Martin, Universidad Autónoma de Madrid, Spain
R. Miranda, Universidad Autónoma de Madrid, Spain
Correspondent: Click to Email
Collective magnetic properties are usually associated to d or f electrons which carry the individual magnetic moments. Band magnetism in organic materials based on π electrons has remained an experimental challenge, in spite of rigorous predictions of a fully spin polarized ground state in half-filled flat band organic systems. Cryogenic Scanning Tunneling Microscopy (STM) and Spectroscopy in UHV and accurate Density Functional Theory (DFT) simulations show that isolated TCNQ molecules deposited on a monolayer of graphene epitaxially grown on Ru(0001) acquire charge from the substrate and develop a sizeable magnetic moment, which is revealed by a prominent Kondo resonance. The magnetic moment is preserved upon dimer and monolayer formation. The self-assembled 2D monolayer of magnetic molecules develops spatially extended spin-split electronic bands visualized in the real space by STM, where only the majority band is filled, thus becoming a 2D, purely-organic magnet whose predicted spin alignment in the ground state is visualized by spin-polarized STM at 4.6 K [1]. Since the added charge occupies spatially extended intermolecular bands with well-defined spin character, one might speculate that the TCNQ monolayer could act as a spin filter or 2D spin polarizer, adding magnetic functionalities to graphene by altering the spin polarization of a current flowing in graphene.

[1] M. Garnica et al, Nature Physics http://dx.doi.org/10.1038/NPHYS2610 (2013)