清华大学电子开关技术改善MRAM储存速度与功耗

来自北京清华大学的研究人员开发出一种新技术，号称能让MARM的储存速度与功耗大幅改善；这种电子开关(electrical switching)技术写入位所需的能源较少。

上述新技术的基本概念，是将磁域开关“部分”开关、而非完全转换其磁场方向；北京清大的研究人员表示，这种方式仍能让MARM储存二进制位，但所需的开关速度却快得多，所耗费的能源量也是会比一般状况少很多。

传统MRAM是利用磁场来开关位单元，使得这种内存的密度不如闪存；不久前，一个日本研究团队也发表了利用电子开关方式执行垂直写入，让MRAM储存密度可获得大幅提升、甚至可超越闪存的方法。北京清大的研究团队则声称，以电子方式开关的MRAM，在速度与功耗方面都优于目前的磁性开关组件。

不同于磁性开关的MRAM位单元需要较复杂的多层堆栈(multilayered stack)，北京清大研究人员所制作的电子开关MRAM位单元，仅只使用了两层不同的铁电薄膜。透过将该双层架构的条纹状扇区间的障壁打散，会产生一种影响其磁性的电子讯号；这会让该架构转换成单一扇区，其薄膜的电阻率也被改变到刚好侦测得到。

北京清大的研究人员证实，在他们的MRAM位单元提供一个电压，能让扇区障壁出现或是消失，用以储存信息。目前该团队正在加强透过让扇区障壁出现或消失所引起的电阻率改变，以优化其材料堆栈、期望可进行商业化。

点击进入参考原文： China researchers claim faster MRAM，by R. Colin Johnson

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China researchers claim faster MRAM

by R. Colin Johnson

MRAM speed can be boosted and power consumption cut by using a new electrical switching technique that requires much less energy to write bits, according to Chinese researchers.

The basic idea is to switch magnetic domains "halfway" rather than to completely reverse their magnetic orientation, which the researchers at Tsinghua University (Beijing) claim still enables MRAMs to store binary bits, but at much faster switching speeds and using a fraction of the energy normally required.

Traditional MRAMs use magnetic fields to switch the state of bit cells, resulting in poor densities compared to flash. This week, Japanese researchers described how MRAMs could utilize electrical switching to perform perpendicular recording that boosts MRAM densities past flash. The Chinese team claims that electrically switched MRAMs can also be made faster and more energy efficient than today's magnetically switched devices.

Unlike magnetically switched MRAM bit cells, which require a complicated multilayered stack, the Chinese researchers constructed their electrically switched MRAM bit cell using just two layers of different ferroelectric films. An electrical signal was shown to be capable of affecting the magnetic polarization of the bit cell by scattering the walls of the striped domain in the bilayered structure. This transformed the structure into a single domain that changed the film's resistivity just enough to detect.

The Chinese researchers demonstrated that applying an electrical voltage to their MRAM bit cell allows the presence or absence of domain walls to be used to store information. They are currently optimizing their material stack for commercialization by enhancing the resistivity change induced by the presence or absence of domain walls.