Browsing by Author "Chang, CR"

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Magnetic force microscopy study of a defect-induced orthogonal magnetic structure on a cobalt film
(2000-02-01)
Lin, HN
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Chang, CR
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Chiou, YH
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電子物理學系
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Department of Electrophysics
An unusual orthogonal magnetic structure is observed on a cobalt film by magnetic force microscopy. The structure is composed of a double wall, which is caused by a surface scratch, and two perpendicular spike domains, which are caused by an internal defect. The occurrence of the structure is attributed to the generation of surface free poles due to film inhomogeneities and their redistribution to reduce the magnetostatic energy. The magnetization pattern has also been proposed to explain the observed magnetic force image. (C) 2000 Elsevier Science B.V. All rights reserved.
Magnetic force microscopy study of domain walls on a thin cobalt film
(1998-05-01)
Lin, HN
;
Chiou, YH
;
Chen, BM
;
Shieh, HPD
;
Chang, CR
Two types of 180 degrees domain walls on a 115 nm cobalt film are observed by magnetic force microscopy. The surface Neel wall on top of an asymmetric Bloch wall is found inhomogeneous. with the width estimated to be around 200 nm. The width of the rhomb-structured cross-tie wall, on the other hand, is approximately 400 nm. The coexistence of these two types of domain walls indicates that their wall energies are comparable at the film thickness. (C) 1998 American institute of Physics.
Positive giant magnetoresistance in ferrimagnetic/Cu/ferrimagnetic films
(2001-06-01)
Lai, CH
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Lin, CC
;
Chen, BM
;
Shieh, HPD
;
Chang, CR
Spin valves composed of ferrimagnetic/Cu/ferrimagnetic layers were fabricated with the magnetization perpendicular to the film planes. By changing the composition of ferrimagnetic layers, both negative and positive giant magnetoresistance (GMR) can be observed in ferrimagnetic spin valves. For samples consisting of both transition-metal (TM-) rich TbFeCo and GdFeCo, negative GMR values were obtained. Due to the high resistivity of amorphous ferrimagnetic films, the shunting effect of Cu led to relatively small MR ratio. The negative MR effect was 1% for 1.7 nm Cu. For spin valves consisting of rare-earth (RE-)rich TbFeCo and TM-rich GdFeCo, positive GMR values were observed. A thin layer of Co was inserted between RE-rich TbFeCo and Cu to manipulate the sign of GMR. (C) 2001 American Institute of Physics.