Dresden 2009 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 17: Magnetic Thin Films I

MA 17.8: Vortrag

Mittwoch, 25. März 2009, 12:00–12:15, HSZ 04

Magnetoelectric phase transition in Fe/Cu(111) — •Lukas Gerhard¹, Toyo K. Yamada¹, Timofey Balashov¹, Albert F. Takács¹, Arthur Ernst², and Wulf Wulfhekel¹ — ¹Physikalisches Institut, Universität Karlsruhe (TH), Germany — ²Max-Planck-Institut für Mikrostrukturphysik, Halle, Germany

Both the crystallographic and the magnetic structure of Fe exhibit a rich phase diagram. Two different crystallographic phases, fcc and bcc, have been reported to coexist in Fe islands on Cu(111) [1]. Comparing our scanning tunnelling spectroscopy to ab-initio calculations, we identified the magnetic ordering of these two phases as layer-wise antiferromagnetic and ferromagnetic. Surprisingly, we observed transitions between these two phases during our STM measurements at 4 K. A systematic study of the tunnelling parameters revealed the electric field of the STM tip as the origin. Applying different electric fields, we could switch between the two different phases on nm scale. The observed coupling of the crystallographic and magnetic structure with an external electric field is explained by a difference in the work function of the two phases and thus evidences Fe/Cu(111) as a multiferroic system.

[1] A. Biedermann, W. Rupp, M. Schmid and P. Varga, Phys. Rev. B 73, 165418 (2006)