China researchers claim faster MRAM

PORTLAND, Ore. -- 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.