• Journal of Magnetics
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• v.1 no.2
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• pp.86-89
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• 1996

The dc magnetron sputter deposited (Pt/Co/Pt/Ni) multilayers which exhibited Curie temperatures in the range of 150-$300^{\circ}C$ were studied as possible alternative multilayers for magneto-optical recording to the widely studied Co/Pt, whose Curie temperatures are in the range of 200~$400^{\circ}C$. The Coercivities of these multilayers were between 450 Oe and 800 Oe. These multilayers exhibited comparable magnetic and magneto-optical properties to Co/Pt multilayers with enhancement of the Kerr rotation at lower wavelengths and negligible Kerr ellipticity over a wide range of the spectrum (4000~7000$\AA$ ).

• Journal of Magnetics
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• v.9 no.4
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• pp.121-124
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• 2004

NiO thickness dependences of perpendicular magnetic anisotropy (PMA) in the $NiO/[CoFe/Pt]_5$ multilayers for exchange biasing and $[CoFe/Pt]_4/Pt/[CoFe/Pt]_4$ for interlayer exchange coupling were investigated. Perpendicular magnetization curve was obtained by out-of-plane extraordinary Hall measurement. Magnetic force microscopy (MFM) has been used for the investigation of magnetic domains on thin films. We confirmed that the interlayer exchange coupling (IEC) as a function of NiO thickness at room temperature existed with a period of two monolayers.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.1
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• pp.36-41
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• 2000

We studied the exchange anisotropy of Ni-Fe/Co-Fe/Mn-Ir/Cu/buffer/Si multilayers using D.C magnetron sputtering technique. Generally, Ni-Fe/Mn-Ir/buffer(Cu)/Si multilayers cannot pin the ferromagnetic layer for the lower exchange biased field. We got $H_{ex}$ ex/ increased by two times, after using Cu/Ta as buffer layer to get larger grain size of Mn-Ir layer and inserting very thin Co-Fe layer between the Ni-Fe layer and the Mn-Ir layer to get improved grain-to-grain epitaxy relation at the interface between Ni-Fe layer and Mn-Ir layer. The variation of $H_{ex}$ by thickness of Mn-Ir layer in ferromagnete/Mn-Ir/buffer/Si multilayers is different to that in Mn-Ir/ferromagnete/buffer/Si multilayers, because the volume distribution of grain size of Mn-Ir layer and the exchange energy at the interface between the Mn-Ir and the ferromagnetic layers is different for stacking sequence.

• Journal of the Korean Magnetics Society
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• v.18 no.3
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• pp.94-97
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• 2008

We investigated how the magnetic anisotropy in $[Co(2\;{\AA})/Ni(8\;{\AA})]{\times}N$ multilayers varied with the type and thickness of an underlayer. The magnetic measurements clearly showed that the perpendicular magnetic anisotropy could be developed in the Co/Ni multilayer by adopting an underlayer with [111] texture. The coercivity of the Co/Ni multilayer increased from 99 Oe to 430 Oe as the thickness of an Au underlayer increased from $50\;{\AA}$ to $500\;{\AA}$. The increase in coercivity is ascribed to the development of the stronger [111] texture in the Co/Ni multilayer as an Au underlayer gets thicker.

• Journal of the Korean institute of surface engineering
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• v.29 no.5
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• pp.386-392
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• 1996

The epitaxial TM/bcc-Cr(001) (TM=Fe, Co, Ni) multilayers have been prepared using MBE. The crystal structure, interlayer exchange coupling and magnetoresistance of those multilayers have been discussed. The structure of Fe, Co and Ni grown on bcc-Cr(001) exhibited bcc(001), distorted hcp(1120) and fcc(110), respectively. In Fe/Cr multilayes, an oscillatory exchange coupling has been observed, but not observed in Ni/Cr system, which may come from the large mixing at interfaces. Large MR ratio (116%, 4.2K) has been obtained in Fe/Cr system, but only 2% in Co/Cr system. This difference can be understood from the view point of the relative potential geight for down spin electrons between TM and Cr.

• Journal of Magnetics
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• v.9 no.2
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• pp.40-46
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• 2004

The magnetic properties of sputtered ($Ni_{83}Fe_{17}/Au/Co/Au$) multilayers with various thicknesses of Au (0.5 {\leq} t_{Au} {\leq} 3 nm), Ni-Fe ($1{\leq}t_{Ni-Fe}{\leq}4nm$) and Co ($0.2{\leq}t_{co}{\leq}1.5nm$) layers were characterized. An alternating in-plane and out-of-plane anisotropy of the ferromagnetic layers was achieved for the structures ($t_{Au}{\geq}1.5nm$) showing a weak coupling between the Ni-Fe layers with an in-plane anisotropy and the Co layers ($0.3{\leq}t_Co{\leq}1.2nm$) with a perpendicular anisotropy. For such a structure, a detailed discussion on the GMR effect is presented, relating to the magnetization reversal from a mutually perpendicular magnetic configuration at the remanence to a parallel one at the saturation. An influence of the dense labyrinth domain structure on the magnetoresistance effect is also addressed.

• Journal of Magnetics
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• v.10 no.2
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• pp.44-47
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• 2005

The oscillatory interlayer exchange coupling (IEC) has been shown in pinned $[CoFe/Pt(t_{pt})/CoFe]/IrMn$ multi-layers with perpendicular anisotropy. The period of oscillation corresponds to about 2 monolayers of Pt. The oscillatory behavior of IEC depending on the nonmagnetic metallic Pt thickness is thought to be related the antiferromagnetic ordering induced by IrMn layer. Oscillatory IEC as function of insulating NiO thickness has been observed in $[Pt/CoFe]_4/NiO(t_{NiO})/[CoFe/Pt]_4$ multilayers. The effect of N (number of bilayer repeats) upon the magnetic property of [Pt/CoFe]N/IrMn is also studied.

• Journal of the Korean Magnetics Society
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• v.9 no.1
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• pp.41-47
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• 1999

$Buffer/[NiFe/Cu/CoFe(Co)/Cu]_N$ spin valve multilayers prepared by dc magnetron sputtering on a corning glass substrate using NiFe and CoFe(Co) posses different coercivities. Dependence of magnetoresistance on the type and thickness of buffer layer, thickness of Cu, NiFe, stacking number of multilayer, substrate temperature and annealing temperature in the form $[NiFe/Cu/CoFe(Co)/Cu]_N$ spin-valve multilayers were investigated. To evaluate effect of magnetoresistance for this samples, X-ray diffraction analysis, vibrating sample magnetometer analysis, and magnetoresistance measurement (4-probe method) were performed the maximum magnetoresistance ratio and coercivity were 7.5 % and 140 Oe, respectively for $Cr-50{\AA}/[NiFe-20{\AA}/Cu-{\AA}/Co-20{\AA}/Cu-50{\AA}]_10$ at substrate temperature of 9$0^{\circ}C$. Magnetoresistance slope maintained 0.25%/Oe until 15$0^{\circ}C$ of annealing temperature, and then decreased to 0.03%/Oe at 20$0^{\circ}C$. It was confirmed that the main factor of thermal stability was deteriorating of soft magnetic properties in the NiFe layer.

• Journal of the Korean Magnetics Society
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• v.8 no.2
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• pp.79-85
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• 1998

The $[Ni_{80}Fe_{20}/Cu/Co/Cu]$ multilayers were grown by evaporation technique, and according to magnetic exchange coupling relation, magnetoresistance ratio and magnetization curve were studied by Co inserting $Ni_{80}Fe_{20}/Cu$ interface. Insertion of Co layer to the antiferromagnetically coupled system, i. e $t_{Cu} = 25\;{\AA}$, decrese the MR ratio contrary to previous reports. However the insertion to the ferromagneticalyl coupled $(t_{Cu} = 27\;{\AA})$ and the noncoupled $(t_{Cu} = 47\;{\AA})$ systems increase the ratio to 3.5 % and 6 % respectively. The results imply that the insertion change the magnetic exchange coupling state as well as the spin dependent scattering of conduction electrons. Besides, insertion of Co layer between Cu and $Ni_{80}Fe_{20}$ layer enhaces thermal stability to the 300 $^{\circ}C$, which indicates that insertion of Co has a role of the effective diffusion barrier.

• Proceedings of the Korean Magnestics Society Conference
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• 1994.10a
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• pp.20-21
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• 1994