Direct Observation of Internal Spin Structure of Magnetic Vortex Cores
A. Wachowiak,
J. Wiebe,
M. Bode,*
O. Pietzsch,
M. Morgenstern,
R. Wiesendanger
Thin film nanoscale elements with a curling magnetic structure
(vortex) are a promising candidate for future nonvolatile data storage
devices. Their properties are strongly influenced by the spin structure
in the vortex core. We have used spin-polarized scanning tunneling
microscopy on nanoscale iron islands to probe for the first time the
internal spin structure of magnetic vortex cores. Using tips coated
with a layer of antiferromagnetic chromium, we obtained images of the
curling in-plane magnetization around and of the out-of-plane
magnetization inside the core region. The experimental data are
compared with micromagnetic simulations. The results confirm
theoretical predictions that the size and the shape of the vortex core
as well as its magnetic field dependence are governed by only two
material parameters, the exchange stiffness and the saturation
magnetization that determines the stray field energy.
Institute of Applied Physics and Microstructure Research Center,
University of Hamburg, Jungiusstr. 11, D-20355 Hamburg, Germany.
*
To whom correspondence should be addressed. E-mail:
mbode{at}physnet.uni-hamburg.de
