Browsing by Author "Chung, TY"

Now showing 1 - 2 of 2

Anisotropy transition of Co in IrMn/Co/FeOx/Co by field cooling
(2006-04-15)
Shen, CT
;
Lai, CH
;
Huang, PH
;
Hsu, SY
;
Chung, TY
The temperature dependence of Co anisotropy on a nano-FeOx layer was studied in the structure of IrMn/Co (FM1)/FeOx/Co (FM2). An anisotropy transition of the FM2 was observed from a combination of uniaxial and unidirectional anisotropies at room temperature (RT) to unidirectional anisotropy at temperature below 80 K through field cooling process. Various ferromagnetic (FM) and antiferromagnetic (AFM) components existing in the FeOx layer were attributable to the observed anisotropy of FM2. AFM domains with T-N higher than room temperature were responsible for the observed uniaxial anisotropy at RT and AFM domains with T-N of 80 K were accountable for the anisotropy transition, below which the unidirectional anisotropy became dominant. In addition, the direction of the shifted loop could be determined by the cooling field direction. (C) 2006 American Institute of Physics.
Detection of the domain structure change using magnetotransport for a series of circular Permalloy dots
(2006-04-15)
Chung, TY
;
Hsu, SY
;
電子物理學系
;
Department of Electrophysics
The magnetic structure of a magnetic dot depends on its geometrical factors such as thickness and dot size and can be either a multidomain state or a vortex state. The magnetoresistance (MR) of a series of magnetic dots with diameters ranging from 0.3 to 5 mu m was measured to investigate the correlation between domain-structure and magnetotransport properties. A dot with a diameter of less than 2 mu m has a domain of vortex state at remanence and demonstrates similar reversible MR results. Moreover, the behaviors of MR show clear changes corresponding to the domain-structure change from vortex to multidomain states with an increasing dot diameter. Data can be qualitatively described by the anisotropic magnetoresistive effect. Hence, our results show that the magnetotransport can be a tool to detect the magnetic domain structure of a submicron magnetic dot. (C) 2006 American Institute of Physics.