New insights into nano-magnetism by spin-polarized scanning tunneling microscopy

Dirk Sander, Hirofumi Oka, Marco Corbetta, Valeri Stepanyuk, Jürgen Kirschner

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

We study the magnetization reversal and the position dependence of the spin-dependent electronic properties of nm small bilayer Co islands on Cu(1 1 1) by spin-polarized scanning tunneling microscopy in magnetic fields at low temperatures of 8 K. The analysis of the energy barrier of magnetization reversal from measurements of the switching field suggests a crossover of the magnetization reversal mode with increasing island size around 7500 atoms from exchange-spring behavior to domain wall formation. The quantitative analysis of the island size dependence of the energy barrier indicates an inhomogeneous magnetic anisotropy of the island. The island rim is magnetically soft, whereas the center shows a pronounced effective anisotropy of 0.148 meV/atom. We speculate that this inhomogeneity of the magnetic anisotropy might be a consequence of the spatial dependence of the spin-dependent electronic properties. We measure a spin-polarization and a tunnel magneto resistance ratio of opposite sign at the rim as compared to the island center.

Original languageEnglish
Pages (from-to)206-215
Number of pages10
JournalJournal of Electron Spectroscopy and Related Phenomena
Volume189
DOIs
Publication statusPublished - 2013
Externally publishedYes

Keywords

  • Electron spin polarization
  • Magnetization reversal
  • Nanomagnetism
  • Scanning tunneling microscopy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Radiation
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Spectroscopy
  • Physical and Theoretical Chemistry

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