Magnets see the light

Light-tunable magnets would work only in the coolest computers. <br>© Getty Images <br>

Light-sensitive ’plastic’ magnets could replace your hard drive.

A ’plastic’ magnet that responds to light could lead to new ways of storing and reading large amounts of computer data. Light would be used to store information in cheap, fast and high-capacity ’magneto-optic’ memories.

The light-switchable magnet is the first to be made from organic (carbon-based) molecules. This means its discoverers, Arthur Epstein of Ohio State University in Columbus and Joel Miller of the University of Utah in Salt Lake City, should be able to use clever chemical tricks to fine-tune the properties of the material1.

Their first goal is to raise the temperature at which the magnetic switching operates. At present, the material works only when cooled to below -198 oC.

Although this sounds impractically low, it is within spitting distance of the temperature at which nitrogen liquefies:
-196 oC. A relatively cheap refrigerant, liquid nitrogen could quite feasibly be used to cool commercial devices incorporating a modified light-sensitive magnet, Epstein and colleagues hope.

Magnetic memories store information in tiny ’magnetized domains’, where magnetic field lines points either ’up’ or ’down’. This allows magnetic media to store the binary (zeros and ones) data of the digital world. In conventional magnetic memories, the direction of the magnetic field is switched electronically; magneto-optic systems do the switching with light, usually from lasers.

There is nothing new about magneto-optic memories. Some commercial hard-disk drives already exist that use light to read and write information stored in magnetic films. But in these systems the laser switches the magnetic medium by warming it.

Epstein and colleagues’ material contains manganese atoms mixed with small organic molecules, and becomes more magnetic when it absorbs blue light. The light alters the shape of the organic molecules, changing their magnetic properties. The researchers can reverse the effect either by shining green light on the material or by heating it above

In a future memory device, information could be encoded in the material as regions of ’stronger’ or ’weaker’ magnetism, which could be written and erased using tightly focused lasers. This could lead to information storage at very high densities.

Epstein admits that applications of this effect are still a long way off – the organic magnet needs a lot of improvement before it has the properties demanded of commercial devices.


  1. Pejakovic, D. A., Kitamura, C., Miller, J. S. & Epstein, A. J. Photoinduced magnetization in the organic-based magnet Mn(TCNE)x.y(CH2Cl2). Physical Review Letters, 88, 057202, (2002).

Media Contact

PHILIP BALL © Nature News Service

All latest news from the category: Information Technology

Here you can find a summary of innovations in the fields of information and data processing and up-to-date developments on IT equipment and hardware.

This area covers topics such as IT services, IT architectures, IT management and telecommunications.

Back to home

Comments (0)

Write a comment

Newest articles

Researchers shrink camera to the size of a salt grain

Micro-sized cameras have great potential to spot problems in the human body and enable sensing for super-small robots, but past approaches captured fuzzy, distorted images with limited fields of view….

World-first product will be a lifesaving traffic stopper

Game-changing technology to design traffic lights that absorb kinetic energy, stopping them from crumpling when hit by a vehicle, will prevent thousands of fatalities and injuries each year and make…

Scientists capture electron transfer image in electrocatalysis process

The involvement between electron transfer (ET) and catalytic reaction at electrocatalyst surface makes electrochemical process challenging to understand and control. How to experimentally determine ET process occurring at nanoscale is…

Partners & Sponsors