Storage Technology: New Discoveries of Magnetic Material Behavior Could Simplify Storage

Geoffrey Beach, assistant professor of materials science and engineering at MIT, and graduate students Uwe Bauer and Satoru Emori, recently reported discoveries in the area of magnetism that have significant implications for magnetic storage.

Beach’s team discovered a method for switching magnetic states by applying a voltage.  The method does not need a magnetic field and requires far less power compared to existing techniques.  It also has the added benefit that once the state is set, it is stably stored, requiring no power except during reads and writes.  Beach said that “for hundreds of years, if you had a magnetic material and you wanted to change the direction in which the material was magnetized, you needed another magnet.”

Professor Beach told Network World that “the idea is not to improve hard disks, but to replace them with magnetic solid-state devices. In a hard disk, bits are fixed in position on the surface of the disk, and individual bits are accessed by physically rotating the disk.  If the bits are instead stored as a series of magnetic domains arranged along a magnetic nanowire, they can be moved by shifting the domains using an electrical current, without any mechanical motion.”

Bauer commented that “the key ingredients of the system are very simple oxide materials.”  The materials used by the MIT research team was gadolinium oxide, a material already commonly used in the manufacture of semiconductor capacitors.

Beach’s team also have an explanation for a phenomenon in magnetism occasionally noticed previously, but had not been reproducible or explained.  In certain circumstances the magnetic domains of a thin ferromagnetic film would flow in a direction exactly opposite of what is normally observed.  Beach showed that the phenomenon could be attributed to the material on which the film is deposited.  The effect that they noticed is called a chiral effect and hadn’t previously been demonstrated with magnetic materials.  The behavior occurs “at room temperature and well above room temperature, and in devices that are ideally suited for integration into electronic devices.”

MIT News quoted Dan Allwood, a materials physics researcher at the University of Sheffield not involved in this research, as saying that the new method “not only offers a novel technical path to control dynamic magnetization processes in patterned nanostructures, but in doing so also presents new physical processes in how voltage can influence magnetic behavior more generally. Understanding the detailed origins of these effects could allow the creation of simple, low-power information-technology devices.”