• Title/Summary/Keyword: Perpendicular anisotropy

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Optical Measurement of Magnetic Anisotropy Field in Nanostructured ferromagnetic Thin Films

  • Whang, Hyun-Seok;Yun, Sang-Jun;Moon, Joon;Choe, Sug-Bong
    • Journal of Magnetics
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    • v.20 no.1
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    • pp.8-10
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    • 2015
  • The magnetic anisotropy field plays an important role in spin-orbit-torque-induced magnetization dynamics with electric current injection. Here, we propose a magnetometric technique to measure the magnetic anisotropy field in nanostructured ferromagnetic thin films. This technique utilizes a magneto-optical Kerr effect microscope equipped with two-axis electromagnets. By measuring the out-of-plane hysteresis loops and then analyzing their saturated magnetization with respect to the in-plane magnetic field, the magnetic anisotropy field is uniquely quantified within the context of the Stoner-Wohlfarth theory. The present technique can be applied to small nanostructures, enabling in-situ determination of the magnetic anisotropy field of nanodevices.

Dependence of Coercivity and Exchange Bias as Surface Magnetic Anisotropy in [Pd/Ferromagnet] Multilayer with Out-of-plane Magnetic Anisotropy (수직자기이방성을 갖는 [Pd/Ferromagnet] 다층막에서 표면자기이방성에 따른 교환력과 보자력의 의존성)

  • Heo, Jang;Kim, Hyun-Shin;Choi, Jin-Hyup;Lee, Ky-Am
    • Journal of the Korean Magnetics Society
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    • v.18 no.3
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    • pp.98-102
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    • 2008
  • Dependence of the exchange bias and coercivity as surface magnetic anisotropy and ferromagnet materials for $[Pd/Co]_N$ and $[Pd/Co,(CoFe)]_N$/FeMn multilayers with perpendicular magnetic anisotropy were investigated. The coercivity was proportionally increased to 670 Oe by increasing stack number N in Ta(2.1 nm)/[Pd(3.1/N)/$Co(1.2/N)]_N$/Ta(2.1) multilayers with perpendicular magnetic anisotropy. Also, the coercivity in exchange biased multilayer was tend to increased by increasing stack number N. But coercivity of each materials have been in order of Co (600 Oe), $Co_5Fe_5$ (520 Oe) and $Co_8Fe_2$ (320 Oe) as function of the ferromagnet materials. The other side, exchange force of each materials is 300 Oe when the reiteration layer number N is 3. In over number of reiteration layer 3, they maintained coercivity between 200 Oe and 300 Oe.

Induced Magnetic Anisotropy of Sputtered FeN Films Due to Substrate Tilting

  • Park, Y.;S. Ryu;S. Jo
    • Journal of Magnetics
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    • v.2 no.1
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    • pp.22-24
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    • 1997
  • FeN thin films were deposited by RF-reactive diode sputtering to investigate magnetic characteristics variation due to substrate tilt during the film deposition, and their magnetic properties were measured by VSM, SEM and AFM. When the substrate tilt pivot edges were parallel to the applied field, the magnetic anisotropy was increased When the substrate tilt pivot edges were perpendicular to the applied field, the easy magnetization axis became the hard magnetization axis, and the hard axis became the easy axis as the tilt angles were increased. The reason is believed to be due to the fact that the tilt induced shape magnetic anisotropy became larger than the field induced magnetic anisotropy by DC magnetic field as the crystal grains are enlongated along the substrate tilt pivot edges due to "oblique incidence anisotropy" commonly found in eveporated thin films.

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Magnetic Anisotropy of Oxygen-deficient Fe/MgO(001) System: An ab Initio Study

  • Choe, Hui-Chae;Jeong, Yong-Jae
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.02a
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    • pp.61-61
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    • 2011
  • Using ab initio calculations, we study the MgO(001) and Fe/MgO(001) surface phases and the effects of interface structure on the Fe/MgO magnetic anisotropy. The surface phase diagrams of MgO(001) and Fe/MgO(001) show that the most stable surface structures are either defect-free surface or the surfaces with oxygen vacancies in c($2{\times}1$) periodicity for the systems. By the formations of the oxygen vacancy rows on MgO(001) surface, the in-plane magnetic anisotropy energy of Fe overlayer is reduced while the perpendicular magnetic anisotropy energy is increased from 0.1 to 0.5 meV per Fe atom.

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Low Writing Field on Perpendicular Nano-ferromagnetic

  • Wibowo, Nur Aji;Rondonuwu, Ferdy S.;Purnama, Budi
    • Journal of Magnetics
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    • v.19 no.3
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    • pp.237-240
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    • 2014
  • For heat-assisted magnetic recording, magnetization reversal probabilities of nano-Pt/MnSb multilayer film with perpendicular magnetic anisotropy under thermal pulse activation were investigated numerically by solving the Landau-Lifshift Gilbert Equation. Magnetic parameters of nano-Pt/MnSb multilayer were used with anisotropy energy of $3{\times}10^5$ erg/cc and saturation magnetization of 2100 G, which offer more than 10 y data stability at room temperature. Scheme of driven magnetic field and thermal pulse on writing mechanism was designed closely to real experiment. This study found that the chosen material is potential to be used as a high density magnetic storage that requires low writing field less than two-hundreds Oersted through definite heating and cooling interval. The possibility of writing data with a zero driven magnetic field also became an important result. Further study is recommended on the thickness of media and thermal pulse design as the essential parameters of the reversal magnetization.

Magnetic circular dichroism measurement of Co films on Pd(111) substrate

  • Kwanghyun Cho;C. C. Whang;Kim, Wookje;Kim, Wondong;Kim, H.-J.;Kim, Jae-Young;Hoon Koh;S.-J Oh;Park, J.-H.
    • Journal of Korean Vacuum Science & Technology
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    • v.5 no.2
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    • pp.33-37
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    • 2001
  • We measured x-ray magnetic circular dichroism of Co films on Pd(111) surface with and without Pd capping layer at the Co L$_2$,$_3$ edges. Perpendicular magnetization and orbital-moment enhancement are induced by the capping layer. The increase of perpendicular magnetic anisotropy induced by capping layer is considered to result from the increase of surface anisotropy due to the hybridization at the surface.

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The oxidation of TaFeCo thin films according to the depositio conditions (제조조건에 따른 TbFeCo 박막의 산화)

  • Mun, Jeong-Tak;Kim, Myeong-Han;Lee, Dong-Cheol
    • Korean Journal of Materials Research
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    • v.4 no.7
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    • pp.767-774
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    • 1994
  • The TbFeCo thin films were prepared by the magnetron sputtering system to investigate the effect of the base pressure, film thickness and pre sputtering on the oxidation of the films by analyzing the change of matneto optical properties and by AES depth profile. The films prepared by the facing targets sputtering system represented almost constant magneto optical properties independent of the base pressure resulting from the short flight distance of the sputtered particles. Also, the thin TbFeCo films represented better perpendicular anisotropy as the films thickness increased with pre sputtering. However, it was still needed a deposition rate higher than a certain critical deposition rate to obtain a perfect perpendicular anisotropy even at a very high film thickness.

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Circularly polarized soft X-ray generation by Co/Pt thin film polarizer with perpendicular magnetic anisotropy

  • Lee, Sang-Hyuk;Huang, Lin;Lee, Jae-Woong;Kim, Namdong;Shin, Hyun-Joon;Jeong, Jong-Ryul;Hwang, Chanyong;Kim, Dong-Hyun
    • Current Applied Physics
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    • v.18 no.11
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    • pp.1196-1200
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    • 2018
  • We have experimentally demonstrated circular polarization generation from linear polarized soft X-ray at synchrotron by adopting a thin magnetic film polarizer. Polarizer is composed of Co/Pt multilayer with a perpendicular magnetic anisotropy, which allows us to easily accommodate without needing any tilting angle into the measurement setup since the circular polarization is generated for the X-ray with normal incidence and transmission. Generated circular polarization is examined by observing magnetic domain features based on the X-ray magnetic circular dichroism, where~11% of circular component is estimated compared to the case of full circular polarization.

Anomalous Nernst Effects of [CoSiB/Pt] Multilayer Films

  • Kelekci, O.;Lee, H.N.;Kim, T.W.;Noh, H.
    • Journal of Magnetics
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    • v.18 no.3
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    • pp.225-229
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    • 2013
  • We report a measurement for the anomalous Nernst effects induced by a temperature gradient in [CoSiB/Pt] multilayer films with perpendicular magnetic anisotropy. The Nernst voltage shows a characteristic hysteresis which reflects the magnetization of the film as in the case of the anomalous Hall effects. With a local heating geometry, we also measure the dependence of the anomalous Nernst voltage on the distance d from the heating element. It is roughly proportional to $1/d^{1.3}$, which can be conjectured from the expected temperature gradient along the sample from the heat equation.