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The best way to put your photos on ice is to freeze them. Extremely cold molecules could soon hold hundreds of times more data than existing hard drives.

By controlling the magnetism of individual molecules, and his colleagues at the University of Manchester in the UK have shown that it may be possible to create hard drives that store more than 30.8 terabits of data per square centimetre. That’s about 5300 full-length movies squeezed into a hard drive that’s just a bit bigger postage stamp.

Of course, there’s a catch. Because the magnetism of these molecules is so unstable, at the moment they need to be cooled to temperatures of -213°C before they’re suitable for data storage. This means it’s unlikely you’ll ever have cold molecule storage in your smartphone, but it could be a convenient way of storing information in data centres such as those run by Google and Facebook.

Magnetism is key to data storage. The hard drives in most desktop computers are divided into lots of tiny magnetised areas that each encode the smallest possible unit of data – one bit, which is either a 1 or a 0. Like fridge magnets, these tiny magnetic areas have a north and south pole, and data is encoded into the hard drive by flipping the direction of each of those magnetic fields.

An orientation in one direction – say, north to south – can represent a 1, while the opposite orientation represents a zero. Crucially, when you turn off a computer’s hard drive, those orientations remain constant – the magnets never ‘forget’ which direction they’re facing.

Single molecules don’t tend to keep their magnetic direction unless they’re held in a magnetic field, making them poor choices for data storage. That’s why, until now, the smallest hard drive was roughly 25 nanometres.

But Chilton’s team has managed to force a molecule to hold on to its magnetic memory at temperatures of -213°C. While this is a record for single molecules, the team are hoping to push this up to -196°C, which is the temperature of liquid nitrogen. If they can do that, data centres could one day be filled with molecular storage and cooled by liquid nitrogen. It even opens up the possibility of molecular data centres in space, where the temperature is a cool -270°C, says Chilton.

at the École Polytechnique Fédérale de Lausanne is impressed by these results. “The molecule needs to be very specifically designed,” he says, to ensure that it retains its magnetic memory. The Manchester team managed to stabilise a single atom of the element dysprosium by attaching two carbon rings to the sides of the element.

Super-cold molecules aren’t the only candidate for the future of data storage. At team at Harvard University has already used CRISPR gene editing to store a video in bacterial DNA, while researchers at the University of Southampton in the UK are using lasers to .

Journal reference: Nature, DOI: 10.1038/nature23447