Data storage: Electrically enhanced recall

December 5, 2012
Data storage: Electrically enhanced recall
A voltage applied across a magnetic tunnel junction increases the device’s energy efficiency, thus enabling smaller devices — potentially as small as 5 nanometers — for higher density data storage. Credit: 2012 A*STAR Data Storage Institute (foreground); Credit: iStockphoto/Thinkstock (background)

Random-access memory (RAM) is a fast electronic device used in computers to temporarily store data. Traditional RAM is based on the flow of electrical current for data processing. To make RAM faster, more energy efficient and capable of storing more information in a smaller volume, hardware developers are investigating RAM based on magnetic fields. Miniaturization of these devices, however, is hampered by thermal instabilities. Hao Meng and his co-workers at the A*STAR Data Storage Institute have now shown how electric fields can help to circumvent this instability in tiny magnetic memories, as well as reduce operating power. "This means more information can be stored in a single chip at a cheaper price," says Meng.

Meng and his team investigated a type of memory that incorporates so-called ' ' (MTJs). Other researchers have previously observed electric-field induced improvements in MTJs, but only in fairly large devices—about 7 micrometers across. Large structures limit the writing speed and suffer from poor compatibility with other electronic components. Meng and his team demonstrated that the concept is also applicable to smaller and faster MTJs that can be integrated more easily.

MTJs are an ideal building block for magnetic memories because of their simplicity and large . In general, they consist of just two separated by a thin insulating barrier (see image). A current passing through the device writes the binary information by controlling the direction of the magnetization in one of the magnetic layers. This process stores information as either a 'one' or a 'zero', depending on whether the induced magnetization is parallel or antiparallel to the magnetization of the second magnetic layer. A measurement of the resistance across the intermediate barrier can then read out the information as it is needed.

The researchers are working to make MTJs smaller so that they can squeeze in more information. However, smaller devices require larger current densities to switch the magnetization: this leads to heating and makes them less efficient. As a workaround, Meng and his co-workers applied just 0.2 volts across electrodes attached to each side of a 150-nanometer MTJ made of CoFeB-MgO. This reduced the required to switch the magnetization by as much as 30% which, in turn, decreased the writing current density.

"Such devices could improve the data transfer rate; that is, how fast you can copy your files from one device to another," says Meng.

Explore further: High-Reliability Read-Method for Spin-Torque-Transfer MRAM, Next-Generation Non-Volatile Memory

More information: Meng, H., Sbiaa, R., Akhtar, M. A. K., Liu, R. S., Naik, V. B. & Wang, C. C. Electric field effects in low resistance CoFeB-MgO magnetic tunnel junctions with perpendicular anisotropy. Applied Physics Letters 100, 122405 (2012).

Related Stories

The art of magnetic writing

August 1, 2011

Computer files that allow us to watch videos, store pictures, and edit all kinds of media formats are nothing else but streams of "0" and "1" digital data, that is, bits and bytes. Modern computing technology is based on ...

Magnetic memories manipulated by voltage, not heat

August 29, 2011

In their search for smaller, faster information-storage devices, physicists have been exploring ways to encode magnetic data using electric fields. One advantage of this voltage-induced magnet control is that less power is ...

Magnetic nanoswitch for thermoelectric voltages

October 24, 2011

The heat which occurs in tiny computer processors might soon be no longer useless or even a problem. On the contrary: It could be used to switch these processors more easily or to store data more efficiently! These are two ...

Recommended for you

Scientists float new approach to creating computer memory

October 8, 2015

What can skyrmions do for you? These ghostly quantum rings, heretofore glimpsed only under extreme laboratory conditions, just might be the basis for a new type of computer memory that never loses its grip on the data it ...

Fusion reactors 'economically viable' say experts

October 2, 2015

Fusion reactors could become an economically viable means of generating electricity within a few decades, and policy makers should start planning to build them as a replacement for conventional nuclear power stations, according ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.