Berlin 2012 – scientific programme

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O: Fachverband Oberflächenphysik

O 72: [MA] Joint Session "Surface Magnetism III" (jointly with O)

O 72.6: Talk

Thursday, March 29, 2012, 16:30–16:45, BH 243

Electric-field induced phase transition in Fe/Ni(111) — •Lukas Gerhard, Moritz Peter, and Wulf Wulfhekel — Physikalisches Institut, Karlsruher Institut für Technologie (KIT), Germany

It is known that both the crystallographic and the magnetic structure of Fe thin films exhibit a rich phase diagram. As has been found recently, this can be exploited to trigger a phase transition in 2 ML thick Fe films by magento electric coupling (MEC) [1]. In order to show that the phenomenon is not limited to this particular system, we studied 1 ML Fe films on a Ni(111) substrate. In atomically resolved scanning tunneling microscopy (STM) images two different crystallographic structures were revealed: Fcc and hcp domains coexist and show slightly different local densities of states. Indeed these domains can be switched by the application of very high electric fields. The induced crystallographic phase transition is studied with atomic resolution showing the lateral displacement of every Fe atom. The dynamic behaviour of the observed transition shows the same characteristics as the MEC in Fe/Cu(111) and can be explained by electric field induced lattice relaxations. A full understanding of the magnetism in this system requires additional theoretical efforts. [1] L. Gerhard et al. Magnetoelectric coupling at metal surfaces. Nat. Nano 5, 792-797 (2010)