Magnetic memory boffins unveil six-state storage design

Better-than-binary multi-level memory

magnet

Memory could be getting an upgrade beyond the two states used in binary, as researchers have designed a magnetic element with six stable magnetic states, according to a paper published in Applied Physics Letters.

The researchers from Bar-Ilan University in Israel and New York University in the US found that by arranging a magnetic film into three crossing ellipses, the overlapping region gave rise to six different magnetic states.

Memory storage is an active area of research. This is not the first time that researchers have made multi-level memory cells with more than two states.

A magnetic storage system has advantages over current electronic storage systems. They consume less power, allow memory to be written and read at a quicker pace, and last longer.

"Our proposal paves the way for enjoying the benefits of multi-level cells in MRAM, making it even more attractive for applications," Lior Klein, a physics professor at Bar-Ilan University and one of the study's lead authors, told Phys.org.

"Furthermore, since MRAM is different in its nature from flash, there is no reason that it should suffer from the drawbacks of multi-level-cell flash memory."

The magnetic states consist of electron spins which point in a certain direction. Each ellipse can hold two states as the electron spins point parallel to its axis in the left or right direction. Applying a current along the direction of the spins controls the orientation of the spins and it can point in six different directions – each one a different state.

This technique, known as spin-orbit torque switching, shows that more memory can be packed over a tighter space. Current methods of increasing memory density involve making the distance between transistors smaller so that more can be crammed onto a chip. This can be risky as states can mix, making storage devices less effective.

"The cost of the memory would probably decrease significantly, and when such bits are incorporated in a magnetic memory array, we may witness other benefits such as increased reading speeds," said Klein.

Researchers believe that even more magnetic states can be created by adding more layers of magnetic film – crossing four ellipses could give eight magnetic states.

Current devices store memory electronically and it'll be a long time before magnetic storage is available to use. The researchers said they would like to "progress towards fabricating a prototype" that would help them "convince the magnetic memory industry to make a shift towards multi-level magnetic memory." ®




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