著者

加藤 大樹 大兼 幹彦 藤原 耕輔 城野 純一 永沼 博 桂田 弘之 安藤 康夫

出版者

公益社団法人 日本生体医工学会

雑誌

生体医工学 (ISSN:1347443X)

巻号頁・発行日

vol.53, no.Supplement, pp.S187_02-S187_02, 2015 (Released:2016-07-09)

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Tunnel magneto-resistance (TMR) effect can be applied to magnetic field sensors because this effect is resistance change of magnetic tunnel junctions (MTJs) by external magnetic field. We have to develop the MTJs with a very high sensitivity (=TMR/2Hk, Hk: magnetic anisotropy field) above 100%/Oe to detect a small bio-magnetic field. In this work, MTJs using CoFeSiB electrode with a low Hk were fabricated. A very high sensitivity of 115%/Oe was achieved by optimization of the CoFeSiB thickness. This sensitivity is the highest value among single MTJ devices and the MTJs with such a high sensitivity can be applied to bio-magnetic field sensor devices.

著者

小野 敦央 大兼 幹彦 永沼 博 安藤 康夫

出版者

公益社団法人 日本生体医工学会

雑誌

生体医工学 (ISSN:1347443X)

巻号頁・発行日

vol.53, no.Supplement, pp.S187_01-S187_01, 2015 (Released:2016-07-09)

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Magnetic tunnel junctions (MTJs) have great advantages for the magnetic field sensor applications. However, a significant improvement of tunnel magneto-resistance (TMR) ratio is needed to detect a small bio-magnetic field. In this study, we fabricated MTJs with half-metallic Co2Fe0.4Mn0.6Si(CFMS) Heusler alloy which are expected to increase TMR ratio. The fabricated MTJswere annealed twice to achieve sensor-type TMR curves. Figure shows the 2nd annealing temperature dependence of TMR curves. In MTJ annealed at 200℃, TMR curve showed a linear resistance response, which is required for sensor applications. This work was supported by the S-Innovation program, Japan Science and Technology Agency (JST).

著者

井浦 聡則 久保田 均 安藤 康夫 宮 照宣

出版者

公益社団法人日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:18804004)

巻号頁・発行日

vol.26, no.6, pp.839-842, 2002-06-01

被引用文献数

3

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The annealing temperature dependence of the tunnel magnetoresistance (TMR) ratio for ferromagnetic tunnel junctions prepared by various oxidation methods was measured. A junction prepared by plasma oxidation showed a TMR ratio of 31.4% before heat treatment, and this ratio increased to 49% after annealing at 300℃ On the other hand, the TMR ratio for a junction prepared by radical oxidation showed a maximum at 350℃. The enhancement of the thermal stability resulted from the different oxidation progress depending on the oxidation method.

著者

窪田 崇秀 児玉 謙司 中村 哲也 桜庭 裕弥 大兼 幹彦 永沼 博 高梨 弘毅 安藤 康夫

出版者

公益社団法人 日本磁気学会

雑誌

Journal of the Magnetics Society of Japan (ISSN:18822924)

巻号頁・発行日

vol.34, no.2, pp.100-106, 2010-03-01 (Released:2010-03-24)

参考文献数

30

被引用文献数

1

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We successfully fabricated L21-ordered Mn2VAl Heusler thin films and evaluated their ferrimagnetic properties by soft x-ray magnetic circular dichroism (XMCD). The buffer layers and annealing temperatures were varied to prepare the Mn2VAl films. We discovered that Mn2VAl could be ordered in an L21 phase well when it was deposited directly onto an MgO (001) single crystalline substrate. The maximum values of L21 and B2 long-range order parameters we obtained were about 0.5 for both phases for samples without a buffer layer, when substrates were heated at 500°C or 600°C. The saturation magnetization (Ms) for these samples was roughly 150 emu/cc. This is rather small compared to that expected from the ideal Slater-Pauling behavior, which might be due to the suppressed degree of L21 or B2 ordering. Ferrimagnetism in the Mn2VAl, ferrimagnetic coupling between Mn and V moments was clearly observed by using the XMCD technique in well-ordered L21-Mn2VAl film as has been predicted in theoretical investigations.