‘Bending current’ current innovation promises energy-efficient magnetic memories
MRAM (Magnetic Random Access Memory) stores data by making smart use of the ‘spin’ of electrons. By using magnetism rather than an electrical charge, the memory is permanent, even when there is a power failure which means that a computer no longer has to be started up. The magnetic memories also use much less power, which means that mobile phones will be able run longer on a battery.
In a MRAM, bits are projected by the direction of the spin of the electrons in a piece of magnetic material: for example, upwards for a ‘1’ and downwards for a ‘0’. The storage of data occurs by flipping the spin of the electrons across to the correct side. Normal practice is to send an electrical current which contains electrons with the required spin direction through the bit. The large quantity of electrical current needed to do this hindered a definitive breakthrough for MRAM, which appeared on the market for the first time in 2006.
A group of TU/e physicists, led by professor Henk Swagten, have published an article describing what is claimed to be a revolutionary method to flip the magnetic bits faster with more energy efficiency. A current pulse is sent under the bit, which bends the electrons at the correct spin upwards, so through the bit.
“It is a bit like a soccer ball that is kicked with a curve when the right effect is applied,” explained Arno van den Brink, TU/e PhD student and the first author of the article.
The new memory is fast but it needs something extra to make the flipping reliable. Earlier attempts to achieve this required a magnetic field but that made the method expensive and inefficient. The researchers have solved the problem by applying a special anti-ferromagnetic material on top of the bits which enables the requisite magnetic field to be frozen, as it were, energy-efficient and low cost.
“This could be the decisive nudge in the right direction for superfast MRAM in the near future,” suggested Van den Brink.
The research findings are published in the journal Nature Communications.
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