New Speed Record for Magnetic Memories

An experiment carried out at the Physikalisch-Technische Bundesanstalt (PTB) has realized spin torque switching of a nanomagnet as fast as the fundamental speed limit allows. Using this so-called ballistic switching future non-volatile magnetic memories could operate as fast as the fastest non-volatile memories. The experiments are described in the next issue of Physical Review Letters (22 August, 2008.

Fast memory chips such as DRAMs and SRAMs (Dynamic and Static Random Access Memory) commonly used today have one decisive disadvantage: in case of power interruption, they lose their stored information. This problem could be solved by magnetic memory chips called MRAMs (Magnetic Random Access Memory). In MRAM the digital information is not stored by means of electric charge but by means of the orientation of the magnetization of a magnetic cell.

The latest generation of MRAM uses the so-called spin torque effect for programming the magnetic bits. Using spin torque the memory state of the cell can be programmed in a very simple way just by applying a current pulse. A positive current switches the magnetization to one direction (digital state “0”) and a negative current to the other (digital state “1”). Spin torque MRAM further promise a high storage density comparable to DRAM and Flash. Most major semiconductor chip producers are developing spin torque memories and market introduction is expected, soon.

A spin torque current pulse excites a rotational motion of the magnetization of the memory cell – the so-called precession. Normally, the magnetization has to undergo several precessional turns before reliable magnetization reversal takes place. Therefore present spin torque MRAM prototypes must operate with rather long write pulses of about 10 nanoseconds duration which limits the MRAM clock speed.

In the experiment carried out at PTB Braunschweig spin torque magnetization reversal has now been realized by a single precessional turn, only. This so called “ballistic” spin torque magnetization reversal corresponds to the ultra short physical limit of spin torque magnetization reversal time. It was achieved by precise tailoring of the current pulse parameters in combination with a small magnetic bias field.

Using ballistic spin torque reversal future MRAM could be programmed by current pulses shorter than 1 nanosecond corresponding to write clock rates well above 1 GHz. It could thus enable a high-density and non-volatile memory operating at the clock rates of the fastest volatile memories.

Original publication:
Quasi-ballistic spin torque magnetization reversal S. Serrano-Guisan, K. Rott, G. Reiss, J. Langer, B. Ocker, and H. W. Schumacher Physical Review Letters 33 (2008)
Dr. Hans Werner Schumacher, PTB Working Group 2.53 Low-dimensional Electron Systems,

Phone: +49531-592-2414, e-mail:

Media Contact

Dr. Hans Werner Schumacher EurekAlert!

Weitere Informationen:

Alle Nachrichten aus der Kategorie: Physics and Astronomy

This area deals with the fundamental laws and building blocks of nature and how they interact, the properties and the behavior of matter, and research into space and time and their structures.

innovations-report provides in-depth reports and articles on subjects such as astrophysics, laser technologies, nuclear, quantum, particle and solid-state physics, nanotechnologies, planetary research and findings (Mars, Venus) and developments related to the Hubble Telescope.

Zurück zur Startseite

Kommentare (0)

Schreib Kommentar

Neueste Beiträge

Who stole the light?

Self-induced ultrafast demagnetization limits the amount of light diffracted from magnetic samples at soft x-ray energies. Free electron X-ray lasers deliver intense ultrashort pulses of x-rays, which can be used…

Could breadfruit be the next superfood?

UBC researchers say yes Breadfruit is sustainable, environmentally friendly and a high-production crop. A fruit used for centuries in countries around the world is getting the nutritional thumbs-up from a…

New calculation refines comparison of matter with antimatter

Theorists publish improved prediction for the tiny difference in kaon decays observed by experiments. -An international collaboration of theoretical physicists–including scientists from the U.S. Department of Energy’s (DOE) Brookhaven National…

By continuing to use the site, you agree to the use of cookies. more information

The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.