The formation and behavior of domain walls were studied in L-shaped nanowires via micro-magnetic simulation using the Objective Oriented Micro-Magnetic Frame program. We induced three types of domain walls by varying the thickness of the nanowire. A transverse wall, an asymmetric transverse wall, and a vortex wall were induced in 10, 20, and 40 nm-thick nanowires, respectively. The type of domain walls formed was determined by the competition between exchange and magnetostatic energy. The depinning field of the domain wall was the largest for the 20 nm-thick and the smallest for the 10 nm-thick nanowires. Domain wall behaviors were quite different from one another. The transverse wall in the 10 nm-thick nanowire was annihilated without changing its type. In the case of the 40 nm-thick nanowire, the vortex wall was not transformed to another type, but did switch its polarity throughout the depinning process. The wall in the 20 nm-thick nanowire underwent repetitions of the transformation of type and the switching of polarity until annihilation. Our results confirm that the behavior of a domain wall at a corner or a rounded part of nanowires is very complex and it originates from the different spin structures of a domain wall.
Bibliographical noteFunding Information:
This research was supported in part by Basic Science Research Program through the National Research Foundation of Korea ( 2010–0015924 ), by the grant from Center for Nanoscale Mechatronics & Manufacturing, one of the 21st Century Frontier Research Programs ( 2010K000189 ) funded by the Ministry of Education, Science and Technology, Korea , and by the IT R&D program of MKE/KEIT (KI002189, Technology Development of 30 nm level High Density Perpendicular STT-MRAM) .
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Metals and Alloys
- Materials Chemistry