下一世代磁性記憶體的挑戰與機會

The Next Generation Magnetic Random- Access Memory: The Opportunities and Challenges

利用自旋軌道矩（spin-orbit torque）作為寫入技術的磁性記憶體（magnetic random access memory），具有更快的寫入速度、更低的消耗功率、更高的耐久度，是極有發展潛力的下一世代非揮發性記憶體。本文將介紹磁性記憶體的優勢和原理，以及自旋軌道矩的產生和其如何翻轉磁矩，並帶出現在面臨的挑戰──如何在無外場下仍可造成磁矩翻轉及降低所需的翻轉電流，最後則介紹除了記憶體的應用之外，其在多階儲存和類神經元計算相關的發展潛力。

The magnetic random access memory (MRAM) that utilizes the spin-orbit torque as the writing method possess a lot of advantages. Faster writing speed, lower power consumption and higher endurance are its merits. Thus it is a highly potential candidate for the next-generation non-volatile memory. In this article, we will introduce the advantages and working principle of MRAM, how to generate the spin-orbit torque and how it switches the magnetic moment. The main challenges for the development of next generation SOT-MRAM are two folds: how to switch the magnetic moment without the external magnetic field and how to further reduce the switching current. Finally, besides its application for memory, we talk about its applications on the multi-level storage and neuromorphic computing.