Magnetic properties of micro-structured exchange coupled bilayers

微结构交换耦合双层的磁性

• 批准号: 09450229
• 负责人: OTANI Yoshichika
• 金额: $ 7.42万
• 依托单位: TOHOKU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09450229/
• 关键词: Exchange coupling; Domain structure; Ferromagnetic dots array; Ferromagnetic wires; Antiferromagnetic domain wall; Magnetoresistance; Antiferromagnet

The purpose of this study is to fabricate 3 dimensionally micro-structured exchange coupled bilayers, and to clarify a responsible mechanism for the exchange coupling field in relation to formation of the antiferromagnetic domains and walls. Amongst transition metal alloys and oxides, Cr-Al or NiO was chosen as an antiferromagnet and FeィイD220ィエD2NiィイD280ィエD2 permalloy was chosen as a ferromagnet. After the structural analyses on the grain size and crystallographic orientations between the ferromagnetic and antiferromagnetic layers with using X-ray diffractometer, atomic force microscope and electron microscope, submicron sized exchange coupled bilayers were fabricated by means of electron-bean lithography. The magnetic domain structure as well as magneto-transport properties were then carefully examined with magnetic force microscope and 4 terminal methods. For the first time, the magnetization reversal processes occurring in the sub-micron region was obtained by analyzing the anisotropy magnetoresistance and the planar Hall effects. The results were compared with the demagnetization curves calculated by micromagnetic simulation. It was found that the exchange coupling field varies proportional to the inverse of the coupling area. Furthermore the slope of the variation was found to reflect the degree of roughness at the interface which determines the strength of the net exchange coupling due to the random exchange field.From this experimental study, the exchange coupling field was shown to be controlled by adjusting the coupling area in submicron scale, which determines the antiferromagnetic domain size.

本研究的目的是制备三维微结构的交换耦合双层膜，并阐明交换耦合场与反铁磁畴和壁形成的关系。在过渡金属合金和氧化物中，选择Cr-Al或NiO作为反铁磁体，并且选择Fe_（220）Ni_（280）D_2坡莫合金作为铁磁体。利用X射线衍射仪、原子力显微镜和电子显微镜对铁磁层和反铁磁层之间的晶粒尺寸和晶体取向进行了结构分析，并利用电子束光刻技术制备了亚微米尺寸的交换耦合双层膜。用磁力显微镜和四端法对样品的磁畴结构和磁输运性质进行了研究。首次通过对各向异性磁电阻和平面霍尔效应的分析，得到了亚微米区域的磁化反转过程。并将计算结果与微磁学模拟计算的退磁曲线进行了比较。结果表明，交换耦合场与耦合面积的倒数成正比。此外，变化的斜率被发现，以反映在界面处的粗糙度，这决定了净交换耦合的强度，由于随机exchange field.From本实验研究，交换耦合场被证明是控制通过调整耦合面积在亚微米尺度，这决定了反铁磁畴的大小。

项目成果

大谷義近: "Cr_<70>Al_<30>/Fe_<19>Ni_<81>2層膜における交換結合磁場と結晶粒径" 日本応用磁気学会誌. 21・5. 911-914 (1997)

大谷芳亲：“Cr_<70>Al_<30>/Fe_<19>Ni_<81>两层膜中的交换耦合磁场和晶粒尺寸”日本应用磁学学会杂志21・5。 914 (1997)

Y. Otani: "Magnetoresistivity of micron size (10・0) epitaxial Co wires"IEEE Trans. Magn.. 35. 2862-2864 (1999)

Y. Otani：“微米尺寸 (10・0) 外延 Co 线的磁阻” IEEE Trans. 35. 2862-2864 (1999)

Y.Otani: "Magnetotransport properties of submicron exchange coupled Fe_<19>Ni_<81>/NiO wires"J. Magn. Magn. Mater.. 198-199. 434-436 (1999)

Y.Otani：“亚微米交换耦合Fe_<19>Ni_<81>/NiO线的磁输运特性”J。

Y.Otani: "Magnetoresistance and Planar Hall effects in submicron exchange-coupled Fe_<19>Ni_<81>/NiO wires" Appl.Phys.Lett.(印刷中). (1999)

Y.Otani：“亚微米交换耦合 Fe_<19>Ni_<81>/NiO 线中的磁阻和平面霍尔效应”Appl.Phys.Lett.（出版中）。

Y.Otani: "Effect of buffer layer on antiferromagnetic grain size and exchange-coupling field of Cr_<70>Al_<30>/Fe_<19>Ni_<81> bilayers"J.Appl.Phys.. 83-11. 7213-7215 (1998)

Y.Otani：“缓冲层对 Cr_<70>Al_<30>/Fe_<19>Ni_<81> 双层反铁磁晶粒尺寸和交换耦合场的影响”J.Appl.Phys. 83-11。