• Title, Summary, Keyword: exchange coupling

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Exchange coupling of Co/NiMn bilayer (Co/NiMn의 교환 자기결합에 관한 연구)

  • 안동환;조권구;주승기
    • Journal of the Korean Magnetics Society
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    • v.10 no.4
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    • pp.171-177
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    • 2000
  • Exchange coupling of Co/NiMn bilayers fabricated by RF magnetron sputtering method was studied. We investigated the variation of exchange coupling field (H$\sub$ex/) for different annealing temperature and time. The maximum exchange coupling field was obtained after 13hr annealing at 300 $^{\circ}C$. With respect to deposition sequence, it was demonstrated that NiMn-top bilayers had higher exchange coupling field than NiMn-bottom bilayers. Ta capping layer was shown to be essential in achieving exchange coupling and Auger Electron Spectroscopy (AES) proved that uncapped NiMn/Co bilayers did not have exchange coupling because of oxygen incorporation into film. We also observed the effect of Ta underlayer on exchange coupling. It was found that Ta underlayer had better not be used for attaining higher exchange coupling. XRD analysis showed that Ta underlayer helped bilayers develop texture, but it was not essential to exchange coupling of Co/NiMn bilayers, which is in contrast to NiFe/NiMn system. Furthermore, the NiMn and Co thickness dependence of exchange coupling has been investigated. The exchange coupling strength reached the maximum above 200 ${\AA}$ NiMn thickness and had inversely proportional relation with Co thickness.

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External Magnetic Field Influence on Exchange Coupling Oscillations in Ultrathin Fe/Au/Tb Film Structures

  • Pogoryelov, Ye.
    • Journal of Magnetics
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    • v.9 no.4
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    • pp.97-100
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    • 2004
  • In the present work exchange coupling between ultrathin Fe ($8{\AA}$) and Tb ($12{\AA}$) layers separated by Au spacer of varied thickness ($3-20{\AA}$) was studied. Anomalous Hall effect measurements showed weakly damped oscillating dependence of the Hall conductivity as a function of Au spacer thickness. Disagreement of the observed damping with the RKKY model of interlayer exchange coupling was explained by the influence of external magnetic field on the behaviour of exchange coupling oscillations. It was confirmed by Hall-like effect measurements at zero applied magnetic field and also illustrated by corresponding estimations.

Spin Exchange Coupling in Dimethoxo-Bridged Dichromium(III) Complexes: A Density Functional Theory Study

  • Kang, Dae-Bok
    • Bulletin of the Korean Chemical Society
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    • v.29 no.5
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    • pp.963-968
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    • 2008
  • For the [$Cr_2(H_2tmp)_2Cl_4$] compound, simplified models with two bridging methoxo ligands have been studied. The influence of the bridging Cr-O-Cr bond angles on the exchange coupling between metal atoms in the model compound has been analyzed by means of density functional calculations with the broken-symmetry approach. Coupling constant calculated for the full structure is in good agreement with the experimentally reported value, confirming the validity of the computational strategy used in this work to predict the exchange coupling in a family of related dinuclear Cr(III) compounds. The calculations indicate a good correlation between the calculated coupling constant and the sum of the squared energy gap of three pairs of metal $t_{2g}$ OMSOs with a limited variation of the Cr-O-Cr angle. The spin density distribution and the mechanism of magnetic coupling interactions are discussed.

Magnetic Exchange Coupling at The Interface of MR/TbCo Thin Films (자기저항 헤드용 MR/TbCo 박막의 자기교환 결합)

  • 서정교;조순철
    • Journal of the Korean Magnetics Society
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    • v.6 no.1
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    • pp.1-6
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    • 1996
  • To simulate the characteristics of magnetic exchange coupling at the interface of MR/TbCo thin films, the directions of magnetizations were calculated by minimizing energy in the films. Newton method and Gauss-Seidel method were used. The width of M-H curve increased with TbCo anisotropy constant, and with the thickness of the transition region of TbCo layer. Hysteresis loop width became extremely narrow (less than 10 Oe of coercivity), when the TbCo transition region length was $400\;\AA$. Also the hysteresis loop of films with low interfacial exchange coupling constant was similiar to that of short transition region length. When interfacial exchange coupling constant was 1/100 of perfect coupling, hysteresis loop showed a coercivity of less than 10 Oe. Comparing the measured hysteresis loop of a fabricated sample with that of simulated one, exchange coupling con¬stant could be estimated.

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Mumetal Growing Temperature Effect on the Exchange Coupling of Cu/mumetal/Al Oxide/Co/Cu Multilayers

  • Lee, Y.W.;Lee, T.H.;Kim, C.G.;Kim, C.O.;Yoon, T.S.;Lee, Y.H.
    • Journal of Magnetics
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    • v.7 no.1
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    • pp.14-17
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    • 2002
  • Magnetic multilayers of a ferromagnetic (FM)/insulator (I)/ferromagnetic (FM) structure have been studied to investigate magnetic exchange coupling between two FM layers. As the Mumetal $(Ni_{77}Fe_{14}Mo_{5}Cu_4$ wt%) growth temperature increases, the grain size and the surface roughness increase simultaneously. The smallest coupling field is obtained at $40^\circ{C}$ where the grain size is larger than that of the $20^\circ{C}$ sample. The exchange coupling field increases again at temperatures higher than $40^\circ{C}$ due to increase in the surface roughness of the Mumetal.

The Exchange Bias of NiO/NiFe Thin Eilm by the Measurement of Anisotropic Mngnetoresistance (이방성 자기저항측정을 이용한 NiO/NiFe 박막의 교환결합연구)

  • Kim, Jong-Kee;Kim, Sun-Wook;Lee, Ky-Am;Lee, Sang-Suk;Hwang, Do-Guwn
    • Journal of the Korean Magnetics Society
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    • v.12 no.4
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    • pp.143-148
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    • 2002
  • We report an experimental evidence of coexistence of the strong and weak exchange couplings in unidirectional NiO/NiFe (antiferromagneticlferromagnetic) bilayer thin films. The exchange bias was measured by VSM and AMR techniques and then, analyzed into the strong and weak exchange couplings by means of a regression method. In NiO(60nm)/NiFe(10nm) film, the ratio of the weak exchange coupling field over the average exchange coupling field was found to be almost unchanged within it range from 0.2 to 0.4 irrespective to the strength of an applied field. However, the ratio increased among the samples with decreasing the average exchange coupling field due to the increment of the weak exchange coupling area.

Effect of the Phase Factor of the Reflection Amplitude on the Interlayer Exchange Coupling in (001) Co/Cu/Co Multilayers

  • Lee, B.C.
    • Journal of Magnetics
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    • v.6 no.2
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    • pp.43-46
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    • 2001
  • The reflection-amplitude approximation is used to calculate the interlayer exchange coupling in (001) Co/Cu/Co multilayers. The dependence of the phase factor of the reflection amplitude on the energy and wave vector is included. The contribution of each period is calculated and the results are compared with those from asymptotic behavior. It is shown that the energy and wave-vector dependence of the phase factor may affect the interlayer exchange coupling significantly.

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Reflection-amplitude Approximation for the Interlayer Exchange Coupling in (001) Co/Cu/Co Multilayers

  • Lee, B. C.
    • Proceedings of the Korean Magnestics Society Conference
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    • pp.191-199
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    • 2000
  • The reflection-amplitude approximation is used to calculate the interlayer exchange coupling in (001) Co/Cu/Co multilayers. The dependence of the phase factor of the reflection amplitude on the energy and wave vector is included. The contribution of each period is calculated and the results are compared with those from the asymptotic behavior. It is shown that the energy and wave-vector dependence of the phase factor may affect the interlayer exchange coupling significantly.

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