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Materials

With an ever-increasing demand for data storage, the race is on to develop new materials that offer greater storage density. Researchers have identified a host of exotic materials that use new ways to pack ‘1’s and ‘0’s into ever-smaller spaces.

And, while many of them are still lab curiosities, they offer the potential to improve data storage density by 100 times or more.


Having a moment

 floppy disks

Data storage technology has moved quickly away from floppy disks (pictured) and CD-DOMs. Image: Pexels

The principle behind many storage media is to use magnetic ‘read’ and ‘write’ heads, an idea also exploited by many of these new technologies – albeit on a much smaller scale.

A good example is recent work from Manchester University, UK, where researchers have raised the temperature at which ‘single molecule magnets’ can be magnetised. Single-molecule magnets could have 100 times the data storage density of existing memory devices.

In theory, any molecular entity can be used to store data as reversing its polarity can switch it from a ‘1’ to a ‘0’. In this case, instead of reading and writing areas of a magnetic disk, the researchers have created single molecules that exhibit magnetic ‘hysteresis’ – a prerequisite for data storage.

 

Researchers discuss the circuit boards in development that negotiate Moore’s Law. Video: Chemistry at The University of Manchester

‘You need a molecule that has its magnetic moment in two directions,’ says Nick Chilton, Ramsay Memorial research fellow in the school of chemistry. ‘To realise this in a single molecule, you need very specific conditions.’

In addition to having a strong magnetic moment, the molecule needs a slow relaxation time – that is, the time it takes for the molecule to ‘flip’ naturally from a ‘1’ to a ‘0’.  ‘If this time is effectively indefinite, it would be useful for data storage,’ he says.

The key is that the molecule itself must have a magnetic moment. So, while a bulk substance such as iron oxide is ‘magnetic’, individual iron oxide particles are not.

 binary digit

A binary digit, or bit, is the smallest unit of data in computing. The system is used in nearly all modern computers and technology. Image: Pixabay

Chilton and his colleagues have identified and synthesised a single-molecule magnet – a dysprosium atom, sandwiched between two cyclopentadienyl rings – that can be magnetised at 60K. This is 46K higher than any previous single-molecule magnet – and only 17K below the temperature of liquid nitrogen.

Being able to work with liquid nitrogen – rather than liquid helium – would bring the cost of a storage device down dramatically, says Chilton. To do this, the researchers must now model and make new structures that will work at 77K or higher.


Bit player

Skyrmions may sound like a new adversary for Doctor Who, but they are actually another swirl-like magnetic entity that could be used to represent a bit of digital data.

doctor who gif

Originally posted by doctorwho247

Scientists at the Max Born Institute (MBI), Germany – in collaboration with colleagues from Massachusetts Institute of Technology, US – have devised a way to generate skyrmions in a controllable way, by building a ‘racetrack’ nanowire memory device that might in future be incorporated into a conventional memory chip.

‘Skyrmions can be conceived as particles – because that’s how they act,’ says Bastian Pfau, a postdoctoral researcher at MBI, as they are generated using a current pulse.

‘Earlier research put a lot of current pulses through a racetrack and created a skyrmion randomly,’ he says. ‘We’ve created them in a controlled and integrated way: they’re created on the racetrack exactly where you want them.’

 Max Born Institute

This racetrack memory device could be incorporated into standard memory chips, say researchers at the Max Born Institute. Credit: Grafix 

In fact, skyrmions can be both created and moved using current pulses – but the pulse for creating them is slightly stronger than the one that moves them. The advantage of using a current pulse is that it requires no moving parts.

The resulting racetrack is a three-layer nanowire about 20nm thick – a structure that will hold around 100 skyrmions along a one-micron length of wire.

While the current research is done ‘in the plane’ with the nanowires held horizontally, Pfau says that in the future, wires could be stacked vertically in an array to boost storage capacity. ‘This would increase the storage density by 100. But this is in the future and nobody has made a strip line that’s vertical yet.’

Could magnetic skyrmions hold the answer to better data storage? Video: Durham University

‘The whole function depends on how you create the multi-layer,’ he says. To stand any chance of being commercialised, which might take six or eight years, Pfau says that new materials will be needed.

However, he is confident this will happen – and that the technology can be merged with ‘conventional’ electronic devices.