Study of the fast domain wall dynamics in thin magnetic wires

• Main Author: Richter, Kornel
• Language: English
• Published: Université Paris Sud - Paris XI 2013
• Subjects: [PHYS:COND:CM_GEN] Physics/Condensed Matter/Other; [PHYS:COND:CM_GEN] Physique/Matière Condensée/Autre; Domain wall dynamics; Amorphous magnetic microwires
• Online Access: http://tel.archives-ouvertes.fr/tel-01004612; http://tel.archives-ouvertes.fr/docs/01/00/46/12/ANNEX/VA2_RICHTER_KORNEL_28082013_Synthese_Annexes.pdf; http://tel.archives-ouvertes.fr/docs/01/00/46/12/PDF/VA2_RICHTER_KORNEL_28082013.pdf

The domain wall dynamics is used in many spintronic devices based on the uniaxial ferromagnetic wires to transport and store information. Therefore, the domain wall velocity is one of the main parameters that determine the operation speed of these devices. Recently, a big attention is being paid to amorphous glass-coated microwires due to the very high domain wall velocities that reach up to 20 km/s. In this work, the fast domain wall propagation in amorphous glass-coated microwires was found in the presence of two main factors: (i) relatively low magnetic anisotropy, (ii) complex geometry of magnetic anisotropies given by internal distribution of mechanical stresses. The domain wall dynamics was examined in amorphous glass-coated microwires of reduced diameter down to 1 μm. It was shown, that the domain wall dynamics in these wires is the same as in wires of bigger diameter. It proves that the high domain wall velocities in microwires are not the effect of microwire diameter value. The direct observation of the surface domain wall structure by use of MOKE microscope confirmed that the domain wall is inclined relatively to the main axis. A new method for magneto-optical observation of the samples with cylindrical geometry was proposed. The inclined structure of the domain wall was found to be partially responsible for the high apparent domain wall velocity measured by the Sixtus-Tonks method in microwires.