Magnetization Processes of Patterned Permalloy Nanostructures
Date Issued
2005
Date
2005
Author(s)
Lai, Mei-Feng
DOI
en-US
Abstract
Abstract
In this thesis we use micromagnetic simulation and experimental method to investigate the magnetization states and magnetization processes of elliptical and ring-shaped patterned thin films that have highly symmetric geometries and smooth boundaries. First we will give a brief introduction to the theoretical background of our research. Various magnetization states and the field-evolution of some states will be described.
From the simulation and experiment the existence of planar buckling mode is demonstrated. Stable magnetization waving structures can be observed within a small field interval before switching. The stable magnetization waving structures are closely related with the boundary condition of the magnetic thin film. Respective regions of the switching mechanism phase diagram is further derived for such buckling-involved reversal mode and vortex-propagation-involved reversal mode. Besides, in the phase boundary we also find a mixed mode of the above two reversal modes, and this reversal mode corresponds to very large switching field.
In the research on ring-shaped magnetic thin films, we find that there exist three stable states that lead to an unconventional triple-switching characteristic. Using magnetoresistance measurement we find that the short circuit effect caused by the patched leads on the magnetic domain walls strongly influences the magnetoresistance characteristic. Besides, magnetoresistance measurement is also used to determine the switching fields of the ring-shaped magnetic thin films. We find that the switching field related with the domain nucleation increases with decreasing of lateral size or with increasing of thickness, and the switching field related with the domain-wall depinning does not have significant lateral-size and thickness dependences.
Subjects
鑄型
薄膜
磁化
奈米
magnetization
patterned
thin film
nano
Type
thesis
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