Browsing by Author "Lee, Shang Fan"

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Magnetization Reversal Characteristics in NiFe Elliptical Ring Arrays
(2010-06-01)
Chang, Liang-Juan
;
Chen, Kuan-Yu
;
Lin, Lu-Kui
;
Yao, Yeong Der
;
Lin, Pang
The magnetization reversal processes of single-layer nanoscale elliptical ring arrays are examined. The magnetic field was applied parallel or perpendicular to the long axis. The magnetization hysteresis loops showed a simultaneous-reversal single-step transition or two-step transition involving flux closure vortex states. For various aspect ratios and thicknesses, the transition between single-step and double-step magnetization reversals was measured to form phase diagrams. Simulations of the magnetization reversal behavior agreed with our results.
Vortex Induced by DC Current in a Circular Magnetic Spin Valve Nanopillar
(2012-04-01)
Chang, L. J.
;
Lin, Pang
;
Lee, Shang Fan
;
材料科學與工程學系
;
Department of Materials Science and Engineering
We investigate the characteristic of vortex states induced by a dc current in trilayer circular magnetic nanopillars experimentally. Our samples are designed such that both the soft and hard layers can contain a magnetic vortex and the interlayer is thick enough such that only dipolar interaction is important. The relative chiralities between the two layers' vortex configurations as functions of external field and current are studied with various diameters. We also perform micromagnetic simulation on the magnetization reversals to compare with the magnetoresistance (MR) curves measured at low current and with current induced magnetization states. The current induced magnetization behaviors due to the spin transfer torque effect and the additional Oersted field are clearly identified on the resistance behavior.