Ultra-High Density Magnetic Memory Cells

我们研究了亚微米磁存储单元的磁性和磁化过程，以期找到提高MRAM（磁随机存取存储器）密度的突破口。我们研究了磁存储器的记录方法。非对称环形点（材料：5- 20nm厚Ni-20at%Fe，直径：500- 1000nm）部分外侧为平面，其磁化方向被面内磁场控制在顺时针和逆时针之间，而普通环形点则需要垂直电流引起的顺时针和逆时针磁场。(2)我们还发现杯形磁记忆单元比环形记忆单元需要更低的磁场来记录。(3) Ni-Fe(10 nm)/Mn-Ir（10 nm）环形点具有固定的磁化方向。(4)利用带导电探针的原子力显微镜可以检测到磁存储器中记录的信息。

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 investigated method for recording magnetic memory. 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.(2) We also have found that the cup-shaped magnetic memory cell required lower magnetic field to be recorded than the ring memory.(3) The Ni-Fe(10 nm)/Mn-Ir(10 nm) ring dot has fixed magnetization direction.(4) The information recorded in the magnetic memory can be detected using atomic force microscopy with conductive probe.