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Hope for molecule memory
- Bengal-made compound for pocket-size storage

New Delhi, Jan. 23: A chemical compound synthesised by scientists in Bengal could lead to molecule-scale memory devices for future information storage systems with capacities 1,000-fold higher than the best available today.

Researchers at the Massachusetts Institute of Technology in the US have used the compound developed at the Indian Institute of Science Education and Research, Mohanpur, and demonstrated its promise to yield molecule-scale memory.

Scientists have for years tried to achieve molecular memory — or store digital data in a single molecule. But all experimental molecules tested so far operate at extremely low temperatures, typically close to –273°Celsius or what is called absolute zero, thus impractical for everyday use.

Now, physicist Jagadeesh Moodera and his colleagues at MIT have shown that an organo-metallic compound synthesised by Swadhin Mandal and his students at IISER may serve as a core component of molecular memory at near room temperature. A paper describing this work, co-authored by the MIT and IISER scientists with other collaborators elsewhere will appear tomorrow in the journal Nature.

“We think we’ve got a very special and a very promising molecule,” said Mandal, an assistant professor of chemical sciences at IISER. “But it primarily establishes a proof of a concept, there’s still a lot more work to be done.”

At MIT, the team led by Moodera sandwiched IISER’s organo-metallic compound between a layer of cobalt and that of copper and found that this layered system could be used to store and read digital information at about –23° Celsius.

“We’re calling this near room temperature but we plan to manipulate the configuration of the organo-metallic compound by changing some of its atoms,” Mandal told The Telegraph.

“We’re hoping such changes in the molecular geometry will make it work at real room temperatures.”

Information storage capacity has dramatically increased over the past decade. “But we’re now approaching the saturation point in storage,” said Karthik Raman, who was a PhD student at MIT and member of the team, but is now a scientist at the IBM India Research Laboratory in Bangalore.

“We’re trying to use a single molecule as a single storage element,” Raman said. “This could give us storage capacities of a 1000 terabytes per square inch, or 1,000 times denser than what is now available in hard drives in the market.”

This research is aimed at harnessing a property of electrons called spin. An electron may have an up or a down spin, and scientists have been trying to use the electron’s up or down spin in molecules as the zero or one states for digital data storage.

The compound developed at IISER contains zinc atoms chemically linked to flat sheets of carbon called graphene fragments. “The lovely thing about this molecule is that we see this reliable effect,” Moodera, a senior research scientist at MIT, said.

"I think it’ll open up new areas for exploration and technology development,” he said.

Concepts for spin-based storage systems developed by Moodera and his colleagues during the 1990s have already been adopted by the information storage industry for high-capacity hard drives. But those ideas are related to bulk memory storage, not molecular memory.

The molecules of the organo-metallic compound bond with cobalt atoms and acquire magnetic properties. The MIT team has shown that an external magnetic field can be used to manipulate the molecule’s magnetisation.

The simple sandwich structure suggests that this molecular system would be easy to manufacture, but researchers caution that the size of the effect they have observed is not large enough yet for a commercial device.

“Fabrication challenges exist and will need to be mitigated for technology development,” Raman said.

But the promise of high density storage beckons.

A typical digital video file takes about one gigabytes. “So (with such a device), you could store more than 1,000 digital movies in a pocket-sized devices.” Raman said. “People will have access to a lot more information in their pockets than ever before.”