APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014;
Denver, Colorado
Session S50: Focus Session: Mesoscopic Materials and Devices I
8:00 AM–11:00 AM,
Thursday, March 6, 2014
Room: Mile High Ballroom 1D
Sponsoring
Unit:
DMP
Chair: John Sarrao, Los Alamos National Laboratory
Abstract ID: BAPS.2014.MAR.S50.2
Abstract: S50.00002 : Adding magnetic functionalities to epitaxial graphene by self assembly on or below its surface
8:36 AM–9:12 AM
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Abstract
Author:
Rodolfo Miranda
(Madrid Institute for Advanced Studies in Nanoscience, Madrid, Spain)
We show how to add magnetic functionalities to graphene's set
of extraordinary electronic, mechanical or optical properties. We will
discuss such two examples:
\begin{enumerate}
\item \textit{Achieving long range magnetic order on a monolayer of TCNQ adsorbed on graphene /Ru(0001). }
\end{enumerate}
Cryogenic STM and Spectroscopy and DFT simulations show that isolated TCNQ
molecules deposited on gr/Ru(0001) [1-3] acquire charge from the substrate
and develop a sizeable magnetic moment, which is revealed by a prominent
Kondo resonance. The self-assembled molecular monolayer develops spatially
extended spin-split electronic bands with only the majority band filled,
thus becoming a 2D organic magnet whose predicted spin alignment in the
ground state is visualized by spin-polarized STM at 4.6 K [4]. The long
range magnetic order is originated by the charge transfer from graphene to
TCNQ (which creates the magnetic moments) \underline {plus} the
self-assembly of the molecular adlayer on the graphene layer (which creates
spin-polarized intermolecular bands where the added electrons partly
delocalize). Examples will be shown where the adsorbed molecules accept
charge and develop magnetic moments, but do nor form bands (F4-TCNQ on
graphene/Ru(0001)), or where similar bands do form, but they are not
populated, because there is no charge transfer to the molecules (TCNQ on
gr/Ir(111)).
ii) \textit{Introducing a giant spin-orbit interaction on graphene/Ir(111) by intercalation of Pb.} The intercalation of an ordered array of Pb atoms below graphene
results in the appearance a series of equally spaced, sharp peaks in the
differential conductance, as revealed by STS at 4.6 K. The vicinity of Pb
enhances the, usually negligible, spin-orbit interaction of graphene. The
spatial variation of the spin-orbit coupling creates a gauge field that acts
as an pseudo magnetic field opening a gap, confining electrons and
originating pseudo Landau levels [5].\\[4pt]
[1] A.L. V\'{a}zquez de Parga et al, Phys. Rev. Lett. \underline {100}, 056807 (2008);\\[0pt]
[2] B. Borca et al, Phys. Rev. Lett. \underline {105}, 036804 (2010);\\[0pt]
[3] D. Stradi et al, Phys. Rev. Lett. \underline {106}, 186102 (2011);\\[0pt]
[4] M. Garnica et al, Nature Physics \underline {9}, 368 (2013);\\[0pt]
[5] F. Calleja et al, in preparation.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2014.MAR.S50.2