Browsing by Author "Peng, TY"

Now showing 1 - 3 of 3

Effects of an Os layer on the magnetic properties of CoFe/IrMn
(2006-04-15)
Peng, TY
;
Lo, CK
;
Chen, SY
;
Yao, YD
;
材料科學與工程學系
The uses of Os as an antidiffusion and buffer layer in IrMn exchange coupled CoFe film were investigated. For the purpose of antidiffusion, the inserted Os layer showed a distinct improvement of S>0.9, with H-C slightly increasing by 1.6 times for the CoFe/Os/MnOs multilayer after 400 degrees C annealing, even though the Os thickness was as thin as 0.3 nm. Furthermore, with a 0.3 nm Os barrier, the 350 degrees C annealed CoFe/Os/IrMn/CoFe showed almost the same magnetic behavior as the as-deposited state, while the H-ex of the upper part of the CoFe/Os/IrMn changed from 100 to 190 Oe. In addition, as a buffer layer, the Os buffer layer could enhance the diffraction peak intensities of IrMn(111)/Os(002) and CoFe (111), and the H-ex of CoFe/IrMn was proportional to the Os thickness. A 120 Oe of H-ex was achieved by using an 11 nm Os buffer layer in a CoFe 10 nm/IrMn 15 nm bottom type film. These results show that Os has the potential to be an antidiffusion and buffer layer in a magnetic multilayer. (C) 2006 American Institute of Physics.
Impedance behavior of spin-valve transistor
(2006-04-15)
Peng, TY
;
Chen, SY
;
Hsieh, LC
;
Lo, CK
;
Huang, YW
The magnetoimpedance (MZ) effect of the pseudo-spin-valve transistor (PSVT) was investigated at room temperature in the frequency ranged from 100 Hz to 15 MHz. The PSVT can be regarded as a complex combination of resistors, inductors, and capacitors, while the impedance (Z) consists of a real part, the resistance (R), and an imaginary part, the reactance (X). Besides, all these components exhibit magnetic hysteresis. It is due to the frequency dependent behavior that R does not reach a minimum at the resonant frequency (f(r)). The frequency dependences of MZ and MX ratios cross zero at f(x)=6.5 MHz and at f(r)=3.65 MHz, respectively. The shape of magnetoreactance (MX) loop is reverse to the magnetoresistance (MR) loop; furthermore, MX ratio changes sign from negative at f < f(r) to positive at f>f(r). The MZ loop also reverses shape and sign after crossing f(x). For instance, the MZ loop with a ratio of 0.077% at 6 MHz switches to -0.086% and -0.125% at 7 and 8 MHz, respectively. (C) 2006 American Institute of Physics.
Study of annealing and exchange bias effects in PtMn based magnetic tunnel junction system
(2004)
Peng, TY
;
Yao, YD
;
Chen, SY
;
Wang, YH
;
Chen, WC
The crystallization structure and thickness of PtMn layer in a magnetic tunnel junction system are important factors to improve its exchange bias effect. This study shows that the PtMn layer could be changed from a FCC (111) structure to a FCT (111) structure after annealing above 270 degreesC. The minimum thickness of PtMn layer is found to be 10 nm for exchange coupling effect to be occurred in our MTJ system. The magnetic exchange effect between PtMn and SAF layers is near 4,300 Oe. Annealing temperatures can be higher than 400 degreesC for samples without patterning; however, temperature at 275 degreesC is too high for samples after patterning. This may be due to the breakdown of edges of the patterned samples as well as the complicated environments around the patterned samples. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.