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PGI-1 Seminar: Dr. Jens Brede

Long-range magnetic coupling between nanoscale organic-metal hybrids mediated by a nanoskyrmion lattice

22 Oct 2014 14:00
PGI Lecture Hall

University of Hamburg, Germany and Donostia International Physics Center, Spain


Spin-polarized scanning tunneling microscopy (SP-STM) enables the study of non-collinear spin-textures at surfaces down to the atomic length scale.  A particularly interesting surface is a single atomic layer thick film of hexagonal Fe on the Iridium(111) surface. Remarkably, the hexagonal atomic lattice exhibits a peculiar square magnetic lattice with a periodicity of about one nanometer in an SP-STM experiment which is sensitive to the out-of-plane component of the magnetization. More recently, the complete vector spin density of the system was mapped experimentally and the magnetic ground state was determined as a square skyrmion lattice (SkX) by first principles calculations. The SkX has no uncompensated magnetic moments and is stable against external magnetic fields up to 9 T at cryogenic temperatures.
Taking advantage of a p-d exchange mechanism and magnetic hardening, I will demonstrate how nanoscale carbon systems, such as graphene islands or coronene molecules locally form organic-ferromagnetic hybrids with tunable magnetic properties (such as anisotropy, moment, coupling,  and coercive field strength) that are embedded within the skyrmion lattice. SP-STM is used to study the response of the hybrids to an external magnetic field up to 6.5 T at a temperature of 6.5 K in ultrahigh vacuum. Remarkably, hybrids embedded in the SkX consisting of as few as 12 Fe-atoms not only show clear hysteric behavior during magnetization reversal but also trigger a shift in the surrounding SkX by half a unit cell. The shift induced in the SkX extends up to several tens of nanometers and enables information transfer via the chiral spin texture of the SkX. The information can be read out directly by STM or by another hybrid coupled to the SkX.


Prof. Dr. Stefan Blügel
Phone: +49 2461 61-4249
Fax: +49 2461 61-2850
email: s.bluegel@fz-juelich.de