Nav: Home

Information storage with a nanoscale twist

March 28, 2017

Swirling objects known as magnetic vortices and skyrmions can be miniaturized without sacrificing mobility, a KAUST-led international research team has found. These findings are relevant for future "race-track" memory technologies that feature massive densities of moveable magnetic bits1.

In nanometer-thin magnetic films, such as iron-nickel alloys, the region separating two magnetic domains or defects can adopt tiny whirlpool-like patterns. Some of these patterns, called skyrmions, resist unraveling even when packed tightly together, and they can also be directed with small electric currents. These features have made the skyrmions attractive targets for research into high-capacity memory devices. One concept zips skyrmions around a loop then past a stationary read/write head to eliminate the need for mechanical components used in today's hard drives.

Aurelien Manchon, an Associate Professor of Material Science and Engineering at the University, notes that one of the main reasons for the appeal of skyrmions is their ability to avoid defects or uneven patches in thin films that would normally trap or "pin" a magnetic charge. However, this agility is compromised when researchers try to shrink skyrmions to the smallest size possible--the smaller they get the more likely they are to get pinned because of the relative increase in defect site dimensions.

To improve these devices, Manchon and international collaborators tried to understand the fundamental momentum transfer between charge currents and magnetic whirlpools.

Using intense x-rays generated at Berkeley University's Advanced Light Source, the team captured time-resolved images of whirlpool patterns called magnetic vortices as they gyrated along a nanometer-wide half-ring track. By pinpointing the position of the vortex core from the imaging sequence, they obtained accurate data about a parameter, known as the non-adiabatic spin-transfer torque, which is crucial for electrical manipulations.

Surprisingly, the measured non-adiabatic torque was far greater than values predicted by existing models. To account for this discrepancy, a theoretical analysis by Manchon showed the extra twisting was provided by another force--the emergent Hall effect, which occurs when electrons travel through a magnetic whirlpool.

"In a nutshell, electrons experience a force that pushes them sideways, but it doesn't come from the local magnetization itself; instead it arises from the topology of the magnetic texture," explained Manchon. "This effect produces an extra spin-polarized current that exerts a torque on the whirlpool."

The researchers found that the additional non-adiabatic torque intensifies when the size of the whirlpool is reduced--a driving force that may offer a way to overcome defect pinning at the nanoscale. "This might be an interesting compromise to seek, especially in the context of skyrmion-based data storage," added Manchon.

King Abdullah University of Science & Technology (KAUST)

Related Electrons Articles:

Hot electrons harvested without tricks
Semiconductors convert energy from photons into an electron current. However, some photons carry too much energy for the material to absorb.
Cooling nanotube resonators with electrons
In a study in Nature Physics, ICFO researchers report on a technique that uses electron transport to cool a nanomechanical resonator near the quantum regime.
New method for detecting quantum states of electrons
Researchers in the Quantum Dynamics Unit at the Okinawa Institute of Science and Technology Graduate University (OIST) devised a new method -- called image charge detection -- to detect electrons' transitions to quantum states.
Slow electrons to combat cancer
Slow electons can be used to destroy cancer cells - but how exactly this happens has not been well understood.
How light steers electrons in metals
Researchers in the Department of Physics of ETH Zurich have measured how electrons in so-called transition metals get redistributed within a fraction of an optical oscillation cycle.
Twisting whirlpools of electrons
Using a novel approach, EPFL physicists have been able to create ultrafast electron vortex beams, with significant implications for fundamental physics, quantum computing, future data-storage and even certain medical treatments.
Inner electrons behave differently in aromatic hydrocarbons
In an international research collaboration between Tsinghua University in Beijing and Sorbonne University in Paris, scientists found that four hydrocarbon molecules, known for their internal ring structure, have a lower threshold for the release of excess energy than molecules without a similar ring structure, because one of their electrons decays from a higher to a lower energy level, a phenomenon called the Auger effect.
Exotic spiraling electrons discovered by physicists
Rutgers and other physicists have discovered an exotic form of electrons that spin like planets and could lead to advances in lighting, solar cells, lasers and electronic displays.
Racing electrons under control
The advantage is that electromagnetic light waves oscillate at petaherz frequency.
Electrons go with the flow
You turn on a switch and the light switches on because electricity 'flows'.
More Electrons News and Electrons Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

Why do we revere risk-takers, even when their actions terrify us? Why are some better at taking risks than others? This hour, TED speakers explore the alluring, dangerous, and calculated sides of risk. Guests include professional rock climber Alex Honnold, economist Mariana Mazzucato, psychology researcher Kashfia Rahman, structural engineer and bridge designer Ian Firth, and risk intelligence expert Dylan Evans.
Now Playing: Science for the People

#541 Wayfinding
These days when we want to know where we are or how to get where we want to go, most of us will pull out a smart phone with a built-in GPS and map app. Some of us old timers might still use an old school paper map from time to time. But we didn't always used to lean so heavily on maps and technology, and in some remote places of the world some people still navigate and wayfind their way without the aid of these tools... and in some cases do better without them. This week, host Rachelle Saunders...
Now Playing: Radiolab

Dolly Parton's America: Neon Moss
Today on Radiolab, we're bringing you the fourth episode of Jad's special series, Dolly Parton's America. In this episode, Jad goes back up the mountain to visit Dolly's actual Tennessee mountain home, where she tells stories about her first trips out of the holler. Back on the mountaintop, standing under the rain by the Little Pigeon River, the trip triggers memories of Jad's first visit to his father's childhood home, and opens the gateway to dizzying stories of music and migration. Support Radiolab today at