Featured Research

from universities, journals, and other organizations

Physicists measure current-induced torque in nonvolatile magnetic memory devices

Date:
March 14, 2011
Source:
Cornell University
Summary:
Tomorrow's nonvolatile memory devices -- computer memory that can retain stored information even when not powered -- will profoundly change electronics, and researchers have discovered a new way of measuring and optimizing their performance.

Tomorrow's nonvolatile memory devices -- computer memory that can retain stored information even when not powered -- will profoundly change electronics, and Cornell University researchers have discovered a new way of measuring and optimizing their performance.

Using a very fast oscilloscope, researchers led by Dan Ralph, the Horace White Professor of Physics, and Robert Buhrman, the J.E. Sweet Professor of Applied and Engineering Physics, have figured out how to quantify the strength of current-induced torques used to write information in memory devices called magnetic tunnel junctions.

The results were published online Feb. 28 in the journal Nature Physics.

Magnetic tunnel junctions are memory storage devices made of a sandwich of two ferromagnets with a nanometers-thick oxide insulator in between. The electrical resistance of the device is different for parallel and nonparallel orientations of the magnetic electrodes, so that these two states create a nonvolatile memory element that doesn't require electricity for storing information. An example of nonvolatile memory today is flash memory, but that is a silicon-based technology subject to wearing out after repeated writing cycles, unlike magnetic memory.

What has held back magnetic memory technology is that it has required magnetic fields to switch the magnetic states -- that is, to write information. This limits their size and efficiency because magnetic fields are long-ranged and relatively weak, so that large currents and thick wires are needed to generate a large-enough field to switch the device.

The Cornell researchers are studying a new generation of magnetic devices that can write information without using magnetic fields. Instead, they use a mechanism called "spin torque," which arises from the idea that electrons have a fundamental spin (like a spinning top). When the electrons interact with the magnets in the tunnel junctions, they transfer some of their angular momentum. This can provide a very strong torque per unit current, and has been demonstrated to be at least 500 times more efficient than using magnetic fields to write magnetic information, Ralph said.

To measure these spin torques, the researchers used an oscilloscope in a shared facility operated by Cornell's Center for Nanoscale Systems. They applied torque to the magnetic tunnel junctions using an alternating current and measured the amplitude of resistance oscillations that resulted. Since the resistance depends on the relative orientation of the two magnets in the tunnel junction, the size of the resistance oscillations could be related directly to the amplitude of the magnetic motion, and hence to the size of the torque.

The researchers hope such experiments will help industry make better nonvolatile memory devices by understanding exactly how to structure them, and also, what materials would best be used as the oxide insulators and the ferromagnets surrounding them.

The work was supported by the National Science Foundation, the Army Research Office and the Office of Naval Research, and included collaborators Chen Wang, graduate student and first author; graduate student Yong-Tao Cui; and Jordan A. Katine from Hitachi Global Storage Technologies.


Story Source:

The above story is based on materials provided by Cornell University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Chen Wang, Yong-Tao Cui, Jordan A. Katine, Robert A. Buhrman, Daniel C. Ralph. Time-resolved measurement of spin-transfer-driven ferromagnetic resonance andspin torque in magnetic tunnel junctions. Nature Physics, 2011; DOI: 10.1038/nphys1928

Cite This Page:

Cornell University. "Physicists measure current-induced torque in nonvolatile magnetic memory devices." ScienceDaily. ScienceDaily, 14 March 2011. <www.sciencedaily.com/releases/2011/03/110309141731.htm>.
Cornell University. (2011, March 14). Physicists measure current-induced torque in nonvolatile magnetic memory devices. ScienceDaily. Retrieved July 23, 2014 from www.sciencedaily.com/releases/2011/03/110309141731.htm
Cornell University. "Physicists measure current-induced torque in nonvolatile magnetic memory devices." ScienceDaily. www.sciencedaily.com/releases/2011/03/110309141731.htm (accessed July 23, 2014).

Share This




More Computers & Math News

Wednesday, July 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Robot Parking Valet Creates Stress-Free Travel

Robot Parking Valet Creates Stress-Free Travel

AP (July 23, 2014) 'Ray' the robotic parking valet at Dusseldorf Airport in Germany lets travelers to avoid the hassle of finding a parking spot before heading to the check-in desk. (July 23) Video provided by AP
Powered by NewsLook.com
Six Indicted in StubHub Hacking Scheme

Six Indicted in StubHub Hacking Scheme

AP (July 23, 2014) Six people were indicted Wednesday in an international ring that took over more than 1,000 StubHub users' accounts and fraudulently bought tickets that were then resold. (July 23) Video provided by AP
Powered by NewsLook.com
The Reviews Are In For The Amazon Fire Phone

The Reviews Are In For The Amazon Fire Phone

Newsy (July 23, 2014) Amazon's first smartphone, the Fire Phone, is set to ship this week, and so far the reviews have been pretty mixed. Video provided by Newsy
Powered by NewsLook.com
Bigger Apple Phone, Bigger Orders

Bigger Apple Phone, Bigger Orders

Reuters - Business Video Online (July 22, 2014) Apple is asking suppliers to make 70 to 80 million units of its new larger screen iPhone, a lot more initially than its current model. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins