스퍼터링 중 외부자기장이 자성박막의 자기적 특성에 미치는 영향

안현태 ( Hyun Tae Ahn ),임상호 ( Sang Ho Lim ),지광구 ( Kwang Koo Jee ),한준현 ( Jun Hyun Han ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.6

A magnetic device which enables the application of a strong and uniform magnetic field to thin film during sputtering was designed for controlling the magnetic anisotropy using a three dimensional finite element method, and the effects of the external magnetic field on the magnetic properties of sputtered thin films were investigated. Both the intensity and the uniformity of the magnetic flux density in the sputter zone (50 mm ×50 mm) was dependent on not only the shape and size of the magnet device but also the magnitude of stray fields from the magnet. For the magnet device in which the distance between two magnets or two pure iron bars was 80-90 mm, the magnetic flux density along the direction normal to the external magnetic field direction was minimum. The two row magnets increased the magnetic flux density and uniformity along the external magnetic field direction. An Fe thin film sputtered using the optimized magnet device showed a higher remanence ratio than that fabricated under no external magnetic field.

Co-Cr(-Ta)/Si 이층막의 자기적 특성

김용진,박원효,금민종,최형욱,김경환,손인환 한국전기전자재료학회 2002 전기전자재료학회논문지 Vol.15 No.3

In odder to investigate the magnetic properties of CoCr-based bilayered thin films on kind of underlayer, we introduced amorphous Si layer to Co-Cr(-Ta) magnetic layer as underlayer. First, we prepared CoCr and CoCrTa single layer using the Facing Targets Sputtering system to investigate theirs properties. It was revealed that with increasing the film thickness of CoCr, CoCrTa single layer, crystalline orientation and perpendicular coercivity was improved. The CoCrTa thin film showed bettor crystalline and magnetic characteristics than CoCr thin film. As a result of investigating magnetic properties of CoCr and CoCrTa magnetic layer on introducing the Si underlayer, perpendicular coercivity and saturation magnetization of CoCr/Si and CoCrTa/Si bilayered thin film were decreased due to the increased grain size and diffusion of Si atoms to magnetic layer. And they showed constant with increasing the film thickness of Si thin film. However, in case of CoCrTa/Si bilayered thin film, in-plane coercivity was controlled low at about 250Oe. The c-axis orientations of CoCr/si and CoCrTa/Si bilayered thin film showed a good crystalline characteristics as about $2^{\circ}$.

수직자성박막에서 자구벽 속도 측정을 통한 샘플 재현성 확인 방법

문준(Joon Moon),이성협(Seong-Hyub Lee),김기태(Kitae Kim),박정현(Jung-Hyun Park),장준영(Jun-Young Chang),유지성(Ji-Sung Yu),최석봉(Sug-Bong Choe) 한국자기학회 2021 韓國磁氣學會誌 Vol.31 No.5

In this study, a method was developed to confirm the deposition reproducibility of the magnetic layer thickness through the magnetic domain wall velocity analysis in the perpendicular magnetic thin film. We analyzed the effect of magnetic layer thickness and magnetic anisotropy on the magnetic domain wall motion occurring in a perpendicular magnetic thin film composed of Pt/Co/Pt. It was confirmed that the creep scaling constant (α) changed rapidly in the thickness regime of the magnetic layer where perpendicular magnetic anisotropy was formed. Using this, it is possible to check the change of α with respect to the change in the thickness of the magnetic layer of several A.

Ion Implantation Effects on CoFeB Magnetic Thin Films

김현빈,오승환,박병국,권호제,윤진문 (사)한국방사선산업학회 2019 방사선산업학회지 Vol.13 No.4

Magnetic thin film materials are used in various electronic device fields. We simulatedthe change of physical properties of magnetic thin film material by ion implantation and conductedexperimental verification. From the simulation results, it was possible to predict the etching byion beam, which showed a decrease in the saturation magnetization. In addition, the simulationresults confirmed that atomic diffusion may occur at the interface between the magnetic thinfilm material and the substrate, and vacancies may occur inside the thin film material. This wasshown to decrease the coercivity due to the decrease of the grain size of the magnetic thin film. Asa result, the decrease in saturation magnetization was minimal due to the ion implantation, butthe coercivity was reduced by more than 2 times, which may contribute to the development of lowpower electronic devices.

Writing and Deleting Magnetic Bubbles using Local Magnetic Fields

Sooseok Lee,Hee-Sung Han,Dae-Han Jung,Namkyu Kim,Myeonghwan Kang,Hye-Jin Ok,Ki-Suk Lee 한국자기학회 2020 Journal of Magnetics Vol.25 No.4

Magnetic bubbles are circular magnetic domains that may occur in thin magnetic films with perpendicular magnetic anisotropy (PMA). Because they can form with high topological stability and can be manipulated by external driving forces, magnetic bubbles have been considered as prominent information carriers, which are set to 1 or 0, corresponding to the presence or absence. For practical applications, such information carriers must be written and deleted in a specific area of the magnetic thin film. Herein, we report that the magnetic bubbles can be written and deleted using local magnetic fields. By applying a localized magnetic field from the magnetic tip of a magnetic force microscopy to the stripe domain structures of the PMA multilayer, bubbles can be written at room temperature via the transformation from stripe domains to magnetic bubbles. The deleting of the bubbles in the targeted area demonstrated by the local magnetic field accompanied by a uniform external field. Our findings can provide a key for manipulating information carriers in the spintronic device based on topological magnetic structures such as magnetic skyrmions and bubbles.

Layer-number dependence of the magnetic properties of MnBi films

Moon, Hongjae,Kim, Sumin,Jung, Hwaebong,Lee, Hyun-Sook,Lee, Wooyoung Elsevier BV * North-Holland 2017 Applied Surface Science Vol.420 No.-

<P><B>Abstract</B></P> <P>We present the effect of multilayer deposition on the magnetic properties of MnBi thin films. The multilayered MnBi films were fabricated with alternating deposition of Bi and Mn with <I>N</I> (<I>N</I> =2–10) layers (L), followed by <I>in situ</I> thermal annealing. As <I>N</I> increases, the even-layered and odd-layered films show a similar layer-number-dependence of the magnetic properties, such as an increasing behavior for <I>H</I> <SUB>c</SUB> and a concave-up behavior for <I>M</I> <SUB>r</SUB> and (<I>BH</I>)<SUB>max</SUB>. Higher magnetic properties were obtained at 9L and 10L. According to the electron microscopy analyses, different morphologies and elemental distributions were observed at different <I>N</I> (e.g., smooth-surfaced MnBi film with Bi islands at 2L and uneven-surfaced MnBi film at 10L). The different distributions of microstructure and chemical components are associated with the layer-dependent magnetic properties of the MnBi films.</P> <P><B>Highlights</B></P> <P> <UL> <LI> MnBi thin films were fabricated using multilayer deposition and in situ annealing. </LI> <LI> The magnetic properties of the MnBi films depended on the number of layers. </LI> <LI> The morphology and chemical composition in the films affect magnetic properties. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Excellent Magnetic Properties of Co₅₃Fe₂₂Hf₁₀O₁₅ Thin Films

L. V. Tho,K. E. Lee,C. G. Kim,C. O. Kim,W. S. Cho 한국자기학회 2006 Journal of Magnetics Vol.11 No.4

Nanocrystalline CoFeHfO thin films have been fabricated by RF sputtering method. It is shown that the CoFeHfO thin films possess not only high electrical resistivity but also large saturation magnetization and anisotropy field. Among the composition investigated, Co?₃Fe₂₂Hf₁?O₁? thin film is observed to exhibit good soft magnetic properties: coercivity (Hc) of 0.18 Oe; anisotropy fild (Hk) of 49.92 Oe; saturation magnetization (4πMs) of 15.5 kG. The frequency response of permeability of the film is excellent. The excellent magnetic properties of this film in addition of an extremely high electrical resistivity (r) of 185 μ㎝ make it ideal for uses in high-frequency applications of micromagnetic devices. It is the formation of a peculiar microstructure that resulted in the superior properties of this film.

Bi(Fe_{0.9}Mn_{0.1})O_{3} 박막의 강유전 및 자기 특성

도달현 한국물리학회 2014 새물리 Vol.64 No.6

Bi(Fe_{0.9}Mn_{0.1})O_{3} (BFMO) thin films were prepared on Pt(111)/Ti/SiO_{2}/Si substrates by using a pulsed laser deposition method. The crystal structure, the oxidation states of the Mn and the Fe ions, and the ferroelectric and the magnetic properties were investigated. There was no changes in the crystal structure of the BFMO thin films compared to the BiFeO_{3} (BFO) thin films. According to the X-ray photoelectron spectroscopy results, Mn²+, Mn³+, Mn⁴+ ions coexisted in the BFMO thin films. Also, the reduced volume fraction of Fe²+ ions, compared to that in BFO thin films, was confirmed. Although ferroelectric hysteresis loops were not observed in the BFMO thin films at low frequencies hysteresis loops were observed at high frequencies. The remnant polarization (2P_{r}) of the BFMO thin film was 156 μC/cm² measured under a 10 kHz voltage pulse. The saturation magnetization (M_{s}) of the BFMO thin film was 4.7 emu/cm³. The magnetic hysteresis loops of the BFMO thin films were similar to these of the BFO thin films. 펄스 레이저 증착법을 이용하여 Pt(111)/Ti/SiO_{2}/Si 기판 위에 Bi(Fe_{0.9}Mn_{0.1})O_{3} (BFMO) 박막을 제작하여 Mn 치환에 따른 결정구조, Mn 및 Fe의 산화수, 강유전 및 자기 특성을 연구하였다. X-선 회절 측정 결과에 의하면, BiFeO_{3} (BFO) 박막과 비교해서, Mn의 치환으로 인한 결정구조에서의 큰 변화는 확인할 수 없었다. BFMO 박막에는 Mn²+, Mn³+, Mn⁴+가 동시에 존재하는 것을 확인하였으며, 순수한 BFO 박막과 비교해서 Fe²+의 양이 줄어들었음을 확인하였다. 순수한 BFO 박막과 비교해서, BFMO 박막의 강유전 특성은 낮은 주파수 영역에서는 도체의 특성을 보인 반면, 높은 주파수 영역에서는 BFO 박막과 유사한 강유전 이력곡선을 얻을 수 있었다. 10 kHz에서 측정된 BFMO 박막의 잔류분극(P_{r})은 2P_{r} = 156 μC/cm² 이었다. 포화 자화값(M_{s})은 4.7 emu/cm³로 Mn의 치환에 따른 자기 특성에서의 변화는 관찰할 수 없었으며, BFO 박막에서 관찰되는 자기 이력곡선과 유사한 특성을 보였다.

The microwave magnetism of epitaxy LiFe5O8 thin film modulated by thickness

Jiao Yang,Jianfei Lei,Kai Du,Xudong Zheng,Xiujuan Jin 한국물리학회 2020 Current Applied Physics Vol.20 No.4

Spinel lithium ferrite LiFe5O8 (LFO) has attracted robust research interests due to their potential applications in isolators, circulators, and phase shifters. In this work, a series of LFO thin film with various thickness were fabricated on SrTiO3 (STO) single-crystalline substrates by pulsed laser deposition technology. We systematically investigated the influences of the thickness of LFO thin film on the crystal structure and magnetic properties. The in-plane lattice parameter a and in-plane lattice parameter c were modulated by controlling the thickness of LFO thin film, which was confirmed using reciprocal space mappings (RSMs) technology. Furthermore, the microwave magnetism of LFO thin film with various thickness were studied systematically by ferromagnetic resonance (FMR) measurement. Moreover, with increasing the thickness of LFO thin film from 50 to 180 nm, the difference of the ferromagnetic resonance field between easy- and hard-magnetization axis can be enhanced and reach to 330 Oe. These results illustrate that dynamic magnetic properties can be controlled by tuning the thickness of LFO thin film. Our work provides an effective method to tailor the lattice parameter and modify the magnetic properties of the LFO thin film and contributes to further design high-frequency functional device.

Thickness induced magnetic anisotropic properties of Tb-Fe-Co thin films

Yüzüak G. Durak,Yüzüak E.,Ennen I.,Hütten A. 한국물리학회 2021 Current Applied Physics Vol.29 No.-

The influence of Tb25Fe61Co14 thin film thicknesses varying from 2 to 300 nm on the structural and magnetic properties has been systematically investigated by using of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, magnetization, and magneto-optic Kerr effect microscopy measurements. Thin film growth mechanism is pursued and controlled by ex-situ X-ray refractometry measurements. X-ray diffraction studies reveal that the Tb25Fe61Co14 films are amorphous regardless of thin films thicknesses. The magnetic properties are found to be strongly related to thickness and preferred orientation. With an increase in film thickness, the easy axis of magnetization is reversed from in-plane to out-of-plane direction. The change in the easy axes direction also affects the remanence, coercivity and magnetic anisotropy values. The cause for the magnetic anisotropy direction change from in-plane to out-of-plane can be related to the preferred orientation of the thin film which depends on the large out-of-plane coercivity and plays an important role in deciding the easy axes direction of the films. According to our results, up to the 100 nm in-plane direction is dominated over the whole system under major Fe-Fe interaction region, after that point, the magnetic anisotropy direction change to the out-of-plane under major Tb-Fe/Tb-Co interaction region and preferred orientation dependent perpendicular magnetic anisotropic properties become more dominated with 2.7 kOe high coercive field values.