Studies on Bloch Line Memory for Practical Use

为了将诺贝尔固态磁存储器（布洛赫线存储器）投入实际使用，在用于10 Mbit/cm^2布洛赫线存储器（标称条宽为5 μ m）的LPE石榴石膜上处理的测试芯片中确认了以下存储器功能。1. 1 mm^2的VBL存储区域通过使用加热磷酸的湿法蚀刻方法形成的平行沟槽图案来构造。2.研制了一台计算机控制的芯片测试机，并通过该测试机验证了多条畴的同时读写操作。3.数值研究了周期性图形化Cr膜引起的应力感生各向异性对比特稳定的影响。根据数值计算结果得到的设计准则制作了一个测试芯片，实现了VBL的比特传输。4.提出了一种具有较大失调容限的主线气泡传播路径结构。加工了一种具有磁泡传播路径的读写门 ...更多信息 在测试芯片上。在该芯片上实现了位信息从VBL到Bubble的转换、Bubble的传播、Bubble的拉伸等顺序门操作，并在40 Mbit/cm^2 Bloch线存储器（标称条宽为2 μ m）的LPE石榴石薄膜上加工了具有合理操作裕度的读写门，以提高位密度。数值模拟了壁面合并过程中微磁结构的时空变化。发现读操作误差是由动态壁结构变化（水平布洛赫线的成核）引起的，并阐明了抑制它的操作条件。此外，还推导出了壁面有效退磁压力的精确计算公式。在材料特性因子较小（q=2.8）的情况下，用该公式模拟的结果与理论符合得很好，可用于大于100 Mbit/cm ^2的布洛赫线存储器。少

In order to put a nobel solid state magnetic memory (Bloch line memory) to practical use, the following memory functions were confirmed in a test chip processed on a LPE garnet film for 10 Mbit/cm^2 Bloch line memory (nominal stripe width is 5 um). 1. VBL storage area of 1 mm^2 was constructed by parallel grooved patterns formed by the wet etching method using heated phosphoric acid. 2. A computer controlled chip tester was fabricated, and the simultaneous read and write operations for multiple stripe domains was confirmed by the chip tester. 3. Bit stabilization effect due to the stress induced anisotropy caused by periodically patterned Cr film was studied numerically. Bit propagation of VBLs was realized in a test chip, which was fabricated according to the design criteria obtained from the numerical results. 4. A new architecture of major line bubble propagation path having large misalignment tolerance was processed. A read-write gate with the bubble propagation path was processed … More on a test chip. Sequential gate operations, that is, conversion of bit informations from VBLs to bubbles, bubble propagation, bubble stretching, were confirmed on the chip.A read-write gate having reasonable operation margin was processed on a LPE garnet film for 40 Mbit/cm^2 Bloch line memory (nominal stripe width is 2 um) as a next step to increase the bit density. The temporal and spatial variations of the detailed micromagnetic structures during the wall merging process was studied numerically. It was found that the read operation error was caused by the dynamic wall structure change (nucleation of the horizontal Bloch line), and the operation condition to suppress it was clarified. Furthermore, An accurate mathematical formula for the effective wall-demagnetizing pressure was derived. The simulated result using the formula agreed well with the theory in the case of material with small characteristics factor (q=2.8), which would be used for Bloch line memory of more than 100 Mbit/cm^2. Less