Scientists at the Massachusetts institute of technology (MIT) and Brookhaven National Laboratory have developed a new approach to control magnetism in thin-film materials, which could eventually enable microchips with much lower power requirements.
The study, published in the journal Nature Materials, suggests that the magnetic properties of a thin-film material can be controlled by applying a small voltage. The resulting changes in the magnetic orientation in the material then continue to remain in the new state, with no need to apply any additional power.
For the past several years, researchers have been trying to develop new technologies that can enhance the performance of silicon microchips, while decreasing their power demands. Spintronics is a technology that promises to be able to boost the performance of microchips by making use of the ‘spin' property of electrons rather than using their negative charge.
Unlike silicon memory chips, spintronic devices don't need a constant supply of power to retain their magnetic properties, which means they need much less power to work. The heat generated in these devices is also very low compared to today's devices.
However, a big challenge in implementation this technology is that researchers are yet to find an easy way that allows quickly controlling the magnetic properties of the material by applying a voltage.
A previous study suggested using oxygen ions to oxidise a thin layer of magnetic material to produce changes in the magnetic properties. However, a big limitation of this approach is that using oxygen ions leads to mechanical damage of the material, making it impractical for computational devices.
The new approach, devised by MIT scientists, relies on using hydrogen ions in place of oxygen ions. Hydrogen ions are much smaller in size and can be inserted/removed from the crystalline structure of the spintronic devices relatively easily, changing the magnetic orientation in the material without damaging it.
"When you pump hydrogen toward the magnet, the magnetisation rotates," says Aik Jun Tan, a graduate student at MIT. "You can actually toggle the direction of the magnetisation by 90 degrees by applying a voltage — and it's fully reversible."
In these devices, information is stored using the orientation of the poles of the magnet, thus making it easy to write and erase ‘bits'.
MIT researchers are currently trying to create a magnetic analog of a transistor.
"I can see lab-based prototypes within a few years or less," said Geoffrey Beach, co-director of the MIT Materials Research Laboratory. "Making a full working memory cell is quite complex and might take longer."
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