Spin-polarized scanning tunneling microscopy and spectroscopy of ferromagnetic Dy(0001)/W(110) films

L. Berbil-Bautista, S. Krause, M. Bode, and R. Wiesendanger
Phys. Rev. B 76, 064411 – Published 8 August 2007

Abstract

Spin-polarized scanning tunneling microscopy and spectroscopy (SP-STS) are employed to investigate the contrast mechanism and the magnetic structure of Dy films epitaxially grown on W(110). While relatively complicated tip preparation procedures were necessary in the past, we now obtain magnetic contrast by bringing the tip in gentle contact with a ferromagnetic Dy film. Maximum contrast is observed at bias voltages around 0.9V. Since highly polarized sample states are not available at the corresponding binding energy, we suggest that an unoccupied tip state is responsible for the strong magnetic contrast. SP-STS measurements show three-, four-, or sixfold magnetic contrast. This result can be explained by random azimuthal orientations of the tip magnetization with respect to the sample’s easy axis. Images of the magnetic domain structure show a stripe domain pattern which consists of about 40nm wide domains, the magnetization directions of which alternate by 60°. This result is a clear proof that the Dy(0001) surface exhibits ferromagnetic order. The domain walls are identified as Néel walls with a width of 25nm.

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  • Received 13 February 2007

DOI:https://doi.org/10.1103/PhysRevB.76.064411

©2007 American Physical Society

Authors & Affiliations

L. Berbil-Bautista*, S. Krause, M. Bode, and R. Wiesendanger

  • Institute of Applied Physics and Microstructure Research Center, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany

  • *Corresponding author; present address: Lawrence Berkeley National Laboratory, Berkeley, CA 94720; ljberbil-bautista@lbl.gov
  • Present address: Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL 60439.

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Vol. 76, Iss. 6 — 1 August 2007

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