Spin dynamics in small magnetic tunnel junctions

小型磁隧道结中的自旋动力学

• 批准号: 15206001
• 负责人: OOGANE Mikihiko
• 金额: $ 28.54万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15206001/
• 关键词: small tunnel junction; spin dynamics; electron beam lithography; focused ion beam; coplanar line; pump-probe method; damping constant; magnetization reversal; 収束イオンブーム

1. Spin injection into nano-area by using micro-fabrication technique(1) Small magnetic tunnel junctions (MTJs) with MgO barrier were fabricated by using focused ion beam (FIB) and electron beam lithography. The minimum size was 100 x 200nm^2 and the resistance x area product of 6Ωμm^2 and the tunnel magnetoresistance (TMR) ratio of 90% were obtained.(2) Spin injection magnetization reversal was successfully observed for the MTJs. The current density was 7.7 x 10^6A/cm^2 and the density increased with increasing the annealing temperature.2. Spin relaxation at the interface of junctions(1) Ferromagnetic resonance (FMR) spectra were measured for Ferromagnet (FeNi)/Nonmagnet (Cu,Ru,Pt) and FeNi/Cu/Pt multilayers and spin relaxation time and spin diffusion length were estimated from the FMR line width. The spin diffusion length of Cu was approximately 350nm and 1000nm at room temperature and liquid He temperature, respectively.(2) FMR spectra were measured for Ferromagnet(FM)/Cu/CoFe multilayers and the increasing ratio of FMR linewidth for the FM was measured. In case of CoFeB as the FM, the linewidth of CoFe increased, on the other hand, the increaseng ratio of CoFeB was small.3. Measurement of response signal by a fast pulse field from a coplanar line(1) For the electrical detection of the spin injection magnetization reversal, a homemade probing apparatus (the pulse width : 1μs, the maximum pulse current : 20mA) was set up. The reversal current depending on the pulse width was measured. The current increased with reducing the pulse width.(2) Pump-probe measurement system was set up in order to measure the spin dynamics in the time scale less than 500ps. The precession signal of permaloy of the size of 180μm x 90μm was measured and the damping parameter α of 0.008 was obtained.(3) The damping parameter of synthetic ferrimagnet was larger than that of FeNi single layer film.

1.利用微加工技术实现纳米区的自旋注入（1）利用聚焦离子束（FIB）和电子束光刻技术制备了具有MgO势垒的小型磁性隧道结（MTJ）。最小尺寸为100 × 200 nm^2，电阻面积积为6Ωμm^2，隧道磁电阻（TMR）比为90%。(2)自旋注入磁化反转成功地观察到的MTJ。电流密度为7.7 × 10^6A/cm^2，电流密度随退火温度的升高而增加.（1）测量了铁磁（FeNi）/非磁（Cu，Ru，Pt）多层膜和FeNi/Cu/Pt多层膜的铁磁共振（FMR）谱，由FMR谱线宽度估算了自旋弛豫时间和自旋扩散长度。Cu的自旋扩散长度在室温和液态He温度下分别约为350 nm和1000 nm。(2)测量了铁磁体（FM）/Cu/CoFe多层膜的铁磁共振谱，并测量了FM的铁磁共振线宽增长率。在CoFeB作为FM的情况下，CoFe的线宽增加，而CoFeB的增加率很小.共面线快脉冲场响应信号的测量（1）为实现自旋注入磁化反转的电探测，自行研制了一套探测装置（脉冲宽度1μs，最大脉冲电流20 mA）。测量取决于脉冲宽度的反转电流。电流随着脉冲宽度的减小而增大。(2)建立了抽运-探测测量系统，用于测量小于500 ps时间尺度的自旋动力学。测量了尺寸为180μm × 90μm的坡莫合金的旋进信号，得到了阻尼参数α = 0.008。(3)合成铁磁材料的阻尼系数大于FeNi单层膜的阻尼系数。

项目成果

宮崎 照宣: "スピンダイナミクス"マテリアルインテグレーション. 16・9. 1-6 (2003)

宫崎辉信：“自旋动力学”材料整合16・9（2003）。

Nanofabrication of magnetic tunnel junctions using electron beam lithography

使用电子束光刻技术纳米制造磁隧道结

• 发表时间: 2004
• 期刊: Journal of Magnetism and Magnetic Materials 272-276
• 作者: M.Taguchi;A.Chainani;K.Horiba;Y.Takata;M.Yabashi;K.Tamasaku;Y.Nishino;D.Miwa;T.Ishikawa;T.Ishikawa;T.Takeuchi;K.Yamamoto;M.Matsunami;S.Shin et al.;Tomohiko Niizeki
• 通讯作者: Tomohiko Niizeki

CO+NH_3 plasma etching for magnetic thin films

磁性薄膜的CO NH_3等离子体刻蚀

• 发表时间: 2004
• 期刊: Journal of Magnetism and Magnetic Materials 272-276
• 作者: E.S.Otabe;I.Kohno;M.Kiuchi;T.Matsushita;T.Nomura;T.Motohashi;M.Karppinen;H.Yamauchi;S.Okayasu;Y.Sasaki;Hitoshi Kubota
• 通讯作者: Hitoshi Kubota

Co_2MnAl ホイスラー合金を用いた強磁性トンネル接合

使用Co_2MnAl Heusler合金的铁磁隧道结

• 发表时间: 2004
• 期刊: 日本応用磁気学会誌 28
• 作者: Miyaura;N.;K.Kuratani;T.Asari;中田 淳
• 通讯作者: 中田 淳

Ji Hyung Yu: "Electron transport properties in magnetic tunnel junctions with epitaxial NiFe (111) ferromagnetic bottom electrodes"Applied Physics Letters. 82. 4735-4737 (2003)

Ji Hyung Yu：“具有外延 NiFe (111) 铁磁底部电极的磁隧道结中的电子传输特性”应用物理快报。