AVS 50th International Symposium
    Magnetic Interfaces and Nanostructures Tuesday Sessions
       Session MI+NS-TuM

Paper MI+NS-TuM3
Imaging of Magnetic Nanoislands at the Thermal Stability Limit

Tuesday, November 4, 2003, 9:00 am, Room 316

Session: Magnetic Imaging and Magnetic Spectroscopies
Presenter: M. Bode, University of Hamburg, Germany
Authors: M. Bode, University of Hamburg, Germany
O. Pietzsch, University of Hamburg, Germany
A. Kubetzka, University of Hamburg, Germany
R. Wiesendanger, University of Hamburg, Germany
Correspondent: Click to Email
Within the past decade spin-polarized scanning tunneling microscopy (SP-STM) became a mature tool for high spatial resolution imaging of the static domain structure of ferro- and antiferromagnetic surfaces.@footnote 1-3@ Recently, we successfully observed the temperature-dependent switching behavior of Fe monolayer islands which were pseudomarphically grown on a Mo(110) substrate and exhibit an perpendicular easy axis. Our SP-STM results show that at temperatures between 15 and 26 K Fe islands consisting of 250-600 atoms (area 20-40 nm@super 2@) are superparamagnetic, i.e., they change their magnetization direction on a time scale of 0.1-1000 s. Small islands were found to switch more often than larger islands as can be expected on the basis of anisotropy barrier considerations. A quantitative analysis reveals, however, that the observed size-dependent variation of the switching rate is much larger than theoretically expected. Possible origins of this behavior are discussed in terms of the island shape and environment. @FootnoteText@@footnote 1@ S. Heinze et al., Science 288, 1805 (2000).@footnote 2@ A. Wachowiak et al., Science 298, 577 (2002).@footnote 3@ M. Bode, Rep. Prog. Phys. 66, 523 (2003).