AVS 45th International Symposium
    Magnetic Interfaces and Nanostructures Technical Group Friday Sessions
       Session MI-FrM

Paper MI-FrM5
Magnetic Properties of Submicron Magnetic Wires Fabricated by e-beam Lithography Investigated by using GMR Effect

Friday, November 6, 1998, 9:40 am, Room 324/325

Session: Magnetization Dynamics and Magneto-Optics
Presenter: T. Ono, Keio University, Japan
Authors: T. Ono, Keio University, Japan
H. Miyajima, Keio University, Japan
K. Shigeto, Kyoto University, Japan
K. Mibu, Kyoto University, Japan
N. Hosoito, Kyoto University, Japan
T. Shinjo, Kyoto University, Japan
Correspondent: Click to Email
The magnetization reversal study of a single submicron magnetic wire is presented. The magnetization reversal in a single submicron magnetic wires can be very sensitively observed by utilizing the giant magnetoresistance (GMR) effect.@footnote 1@ GMR is the electrical resistance change accompanied with the change of magnetic structure. This means, in turn, the magnetic structure of the system can be determined from the resistivity measurements. In a wire case, the magnetic shape anisotropy restricts the direction of the magnetization to be parallel or antiparallel along the wire axis. The GMR change is directly proportional to the magnitude of the switching layer magnetization. A single NiFe(40nm)/Cu(20nm)/NiFe(5nm) trilayer wire 500 nm in width was prepared. An artificial neck was introduced in the wire. The temperature dependences of the nucleation field and the propagation velocity of the magnetic domain wall in the wire were studied by using the GMR effect. The result clearly shows that the artificial neck works as a pinning center for the magnetic domain wall. The temperature dependence of the nucleation field in a single submicron magnetic wire was investigated by measuring the coercive field at which the electrical resistance abruptly changes by the GMR effect. The nucleation field shows a thermal excitation behavior down to 5 K. The study at lower temperatures, down to 50 mK, is now in progress. By measuring the time dependence of the resistance during the magnetization reversal, the propagation velocity of the magnetic domain wall was estimated. Under the external magnetic field of 90 Oe, the velocity in the NiFe layer (40 nm in thickness and 500 nm in width ) is about 5 cm/s at 77 K, the velocity of which is much smaller than that reported by Sixtus and Tonks for bulk NiFe wire in 1931.@footnote 2@ @FootnoteText@ @footnote 1@T. Ono, H. Miyajima, K. Shigeto and T. Shinjo, Appl. Phys. Lett. 72, 1116 (1998). @footnote 2@K.J. Sixtus and L. Tonks, Phys. Rev. 37, 930 (1931).