Single-molecule-level data storage may achieve 100 times higher data density

Imagine storing more than 25 terabytes of data in a device the size of a U.S. quarter or British 50p coin
August 28, 2017

(credit: iStock)

Scientists at the University of Manchester have developed a data-storage method that could achieve 100 times higher data density than current technologies.*

The system would allow for data servers to operate at the (relatively high) temperature of -213 °C. That could make it possible in the future for data servers to be chilled by liquid nitrogen (-196 °C) — a cooling method that is relatively cheap compared to the far more expensive liquid helium (which requires -269 °C) currently used.

The research provides proof-of-concept that such technologies could be achievable in the near future “with judicious molecular design.”

Huge benefits for the environment

Molecular-level data storage could lead to much smaller hard drives that require less energy, meaning data centers across the globe could be smaller, lower-cost, and a lot more energy-efficient.

Google data centers (credit: Google)

For example, Google currently has 15 data centers around the world. They process an average of 40 million searches per second, resulting in 3.5 billion searches per day and 1.2 trillion searches per year. To deal with all that data, Google had approximately 2.5 million servers in each data center, it was reported in 2016, and that number was likely to rise.

Some reports say the energy consumed at such centers could account for as much as 2 per cent of the world’s total greenhouse gas emissions. This means any improvement in data storage and energy efficiency could also have huge benefits for the environment as well as vastly increasing the amount of information that can be stored.

The research, led by David Mills, PhD, and Nicholas Chilton, PhD, from the School of Chemistry, is published in the journal Nature. “Our aim is to achieve even higher operating temperatures in the future, ideally functioning above liquid nitrogen temperatures,” said Mills.

* The method uses single-molecule magnets, which display “hysteresis” — a magnetic memory effect that is a requirement of magnetic data storage, such as hard drives. Molecules containing lanthanide atoms have exhibited this phenomenon at the highest temperatures to date. Lanthanides are rare earth metals used in all forms of everyday electronic devices such as smartphones, tablets and laptops. The team achieved their results using the lanthanide element dysprosium.

Abstract of Molecular magnetic hysteresis at 60 kelvin in dysprosocenium

Lanthanides have been investigated extensively for potential applications in quantum information processing and high-density data storage at the molecular and atomic scale. Experimental achievements include reading and manipulating single nuclear spins, exploiting atomic clock transitions for robust qubits and, most recently, magnetic data storage in single atoms. Single-molecule magnets exhibit magnetic hysteresis of molecular origin—a magnetic memory effect and a prerequisite of data storage—and so far, lanthanide examples have exhibited this phenomenon at the highest temperatures. However, in the nearly 25 years since the discovery of single-molecule magnets, hysteresis temperatures have increased from 4 kelvin to only about 14 kelvin using a consistent magnetic field sweep rate of about 20 oersted per second, although higher temperatures have been achieved by using very fast sweep rates (for example, 30 kelvin with 200 oersted per second). Here we report a hexa-tert-butyldysprosocenium complex—[Dy(Cpttt)2][B(C6F5)4], with Cpttt = {C5H2tBu3-1,2,4} and tBu = C(CH3)3—which exhibits magnetic hysteresis at temperatures of up to 60 kelvin at a sweep rate of 22 oersted per second. We observe a clear change in the relaxation dynamics at this temperature, which persists in magnetically diluted samples, suggesting that the origin of the hysteresis is the localized metal–ligand vibrational modes that are unique to dysprosocenium. Ab initio calculations of spin dynamics demonstrate that magnetic relaxation at high temperatures is due to local molecular vibrations. These results indicate that, with judicious molecular design, magnetic data storage in single molecules at temperatures above liquid nitrogen should be possible.