Magnetic Vortex Core Observation in Circular Dots of Permalloy
T. Shinjo,1*
T. Okuno,1
R. Hassdorf,1
K. Shigeto,1
T. Ono2
Spin structures of nanoscale magnetic dots are the
subject of increasing scientific effort, as the confinement of spins
imposed by the geometrical restrictions makes these structures
comparable to some internal characteristic length scales of the magnet.
For a vortex (a ferromagnetic dot with a curling magnetic structure), a
spot of perpendicular magnetization has been theoretically predicted to
exist at the center of the vortex. Experimental evidence for this
magnetization spot is provided by magnetic force microscopy imaging of
circular dots of permalloy (Ni80Fe20) 0.3 to 1 micrometer in diameter and 50 nanometers thick.
1 Institute for Chemical Research, Kyoto
University, Uji 611-0011, Japan.
2 Faculty of
Science and Technology, Keio University, Yokohama 223-8522, Japan.
*
To whom correspondence should be addressed. E-mail:
shinjo{at}scl.kyoto-u.ac.jp