2007 Fiscal Year Final Research Report Summary
Fabrication of epitaxial heterostructures with halrf-metallic ferromagnets and development of spin-controlled devices
| Project/Area Number |
18360143
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Electronic materials/Electric materials
|
|---|
| Research Institution | Hokkaido University |
|---|
Principal Investigator |
YAMAMOTO Masafumi Hokkaido University, Graduate School of Information Science and Technology, Professor. (10322835)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
UEMURA Tetsuya Hokkaido University, Graduate School of Information Science and Technology, Associate Prof. (20344476)
MATSUDA Ken-ichi Hokkaido Univ, Graduate School of Information Science and Techonlogy, Assistant Prof. (80360931)
SAITO Toshiaki Toho University, Faculty of Science, Department of Physics, Professor (80170512)
|
|---|
| Project Period (FY) |
2006 – 2007
|
| Keywords | half-metallic ferromagnets / Heusler alloy / ferromagnetic tunnel junctions / tunnel magnetoresistnce / spintonics / スピントロニクス |
|---|
| Research Abstract |
The purpose of the present study was to develop spintronic devices utilizing the half-metallicity of Co-based Heusler alloys (Co_2YZ). Fully epitaxial magnetic tunnel junctions (MTJs) with a Co_2YZ thin film or Co_2YZ thin films and a MgO barrier featuring abrupt and extremely smooth interfaces were fabricated. Furthermore, high tunnel magnetoresistance (TMR) ratios were demonstrated at room temperature (RT) for fabricated Co_2YZ/MgO-based MTJs. The main results are summarized as follows.
1) The Heusler alloy-based MTJ device technology was developed. This device technology features the followings: a) all layers in the MTJ trilayer structures are epitaxial and single-crystalline, b) abrupt and atomically flat interfaces between a Co_2YZ (Co_2Cr_<0.6>Fe_<0.4>Al (CCFA), Co_2MnSi (CMS), or Co_2MnGe) thin film and a MgO tunnel barrier, and c) the interface region of CMS thin films underneath a MgO barrier is not oxidized.
2) The fabricated CCFA/MgO/Co_<50>Fe_<50> MTJs demonstrated a high TMR ratio of 109 % at RT (317% at 4.2 K).
3) Fully epitaxial exchange-biased MTJs with CMS thin films as both lower and upper electrodes and with a MgO barrier were fabricated.
The TMR ratios at both RT and 4.2 K increased with increasing the in-situ annealing temperature (T_a) just after the deposition of the upper CMS electrode. Furthermore, a high TMR ratio of 179% at RT (683% at 4.2 K) was demonstrated.
In summary, it was demonstrated that epitaxial, single-crystalline heterostructures consisting of Co_2YZ thin films and a MgO barrier are highly promising for spintronic devices that utilize the half-metallicity of Co-based Heusler alloys.
|
-
-
-
-
-
-
-
-
[Journal Article] Electronic and magnetic properties of Heusler alloy Co_2MnSi epitaxial ultrathin films facing a MgO barrier studied by X-ray magnetic circular dichroism2008
Author(s)
T. Saito, T. Katayama, A. Emura, N. Sumida, N. Matsuoka, T, Ishikawa, T Uemura, M. Yamamoto, D. Asakura, and T. Koide
-
Journal Title
J. Appl Phys 103
Pages: 07D712-1-07D712-3
Description
「研究成果報告書概要(欧文)」より
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
[Presentation] "Electronic and magnetic properties of Heusler alloy Co_2MnSi epitaxial ultrathin films facing a MgO barrier investigated by X-ray magnetic circular dichroism"2007
Author(s)
T. Saito, T. Katayama, A. Emura, N. Sumida, N. Matsuoka, T. Ishikawa, T. Uemura, M. Yamamoto, D. Asakura, and T. Koide
Organizer
Abstract of the 52^<nd> Magnetism and Magnetic Materials Conference
Place of Presentation
Tampa, Florida, USA
Year and Date
2007-11-06
Description
「研究成果報告書概要(欧文)」より
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
