2002 Fiscal Year Final Research Report Summary
Ultra-High Density Magnetic Memory Cells
| Project/Area Number |
12450013
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Applied materials science/Crystal engineering
|
|---|
| Research Institution | Osaka University |
|---|
Principal Investigator |
NAKATANI Ryoichi Graduate School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (60314374)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
KAMADA Yasuhiro Graduate School of Engineering, Assistant Professor (Faculty of Engineering, Iwate University, Associate Professor, at present), 大学院・工学研究科(現 岩手大学・工学部), 助手(現 助教授) (00294025)
ENDO Yasushi Graduate School of Engineering, Assistant Professor, 大学院・工学研究科, 助手 (50335379)
YAMAMOTO Masahiko Graduate School of Engineering, Professor, 大学院・工学研究科, 教授 (30029160)
|
|---|
| Project Period (FY) |
2000 – 2002
|
| Keywords | information memory device / magnetic random access memory / memory cell / magnetic state / stray field / memory layer / ring memory cell / closure domain |
|---|
| Research Abstract |
We have investigated magnetic properties and magnetization processes of sub-micron magnetic memory cells in order to find a breakthrough that increases a density of MRAM (magnetic random access memory).
(1) We have established a microfabrication process that makes rectangular memory cells (70 nm x 200 nm). The size corresponds a memory volume of 16 Gbits.
(2) Magnetic states of the Ni-Fe(5 nm)/Hf(5 nm) rectangular cells and Ni-Fe(5 nm)/Hf(2 nm)/Ni-Fe(5 nm)/Hf(5 nm) rectangular cells were observed using magnetic force microscopy. The observation showed that the magnetic flux closed through the two magnetic layers in the Ni-Fe/Hf/Ni-Fe/Hf cells, and the closed magnetic flux decreased the switching field of the Ni-Fe/Hf/Ni-Fe/Hf cells. The micromagnetics simulation showed that the switching field of the Ni-Fe/Hf/Ni-Fe/Hf cells is about 1/2 of the Ni-Fe/Hf cells for the cell size of 50 nm x 100 nm.
(3) The micromagnetics simulation showed that the magnetization direction of the asymmetric ring dots (material: 5-20 nm thick Ni-20at%Fe, diameter. 500-1000 nm) that have partly planed outer sides were controlled between clockwise and counterclockwise by in-plane magnetic fields, even though the ordinary ring dots needed the clockwise and counterclockwise magnetic fields caused by the perpendicular current.
|
