In a research first that could lead to a new generation of hard drives capable of storing thousands of movies per square inch, physicists at Rice University have decoded the three-dimensional structure of a tornado-like magnetic vortex no larger than a red blood cell.
"Understanding the nuances and functions of magnetic vortices is likely going to be a key in creating next-generation magnetic storage devices," said lead researcher Carl Rau, professor of physics and astronomy. "It's widely believed this technology will support storage densities in the range of terabits per square inch, and our group is equally excited about the potential for magnetic processors and for high-speed magnetic RAM."
The findings are available online and due to appear in an upcoming issue of Physical Review Letters.
Rau and postdoctoral researcher Jian Li used a one-of-a-kind scanning ion microscope to first create and then measure ultra-thin circular disks of soft magnetic cobalt. Their goal was to trap and image a single magnetic vortex, a cone-like structure that's created in the magnetic field at the disk when all the magnetic moments of the atoms in the disk align into uniform concentric circles. However, towards the core of the disk, the magnetic moments point more and more out of the plane of the disk, like a swirling cone. If the vortex spins in a right-handed direction, the cone points up, and if the vortex spins left, the cone points down.
In searching for the right sized disk to create the phenomenon, Rau and Li used thin films of cobalt --about the thickness of a cell membrane. They made disks with diameters as large as 38 microns – about half the width of a human hair – and as small as one micron – about the size of a bacterium. The single vortex was found on disks measuring six microns in diameter, slightly smaller than a red blood cell.
"Most people are familiar with the vortex: we see it in satellite photos of hurricanes, in whirlpools and in bathtub drains – even in Van Gogh's famous painting 'Starry Night,'" Rau said. "In nanomagnetism, however, vortices are quite hard to see experimentally. Most often, we must infer their existence from some other measurement.
"Our high-resolution spin microscope is the exception here," he said. "It allows us to map not just the overall vortex, but also the detailed location and orientation of millions of magnetic moments that combine physical forces to create the overall structure."
The instrument Rau and Li used in the study is a scanning ion microscope with polarization analysis, or SIMPA. The device consists of a highly-focused ion beam that fires gallium ions at surfaces of flat cobalt samples. The beam is first used to etch away the cobalt around each circular disk. Then, using a different setting, the gallium ions are fired at the cobalt surface in such a way as to induce the release of electrons. The electrons, which carry specific information about the magnetic state of the cobalt atoms that release them, are captured by a detector and analyzed.
Rau said better understanding of magnetic vortices could allow breakthroughs in the design of nanostructures for ultra-high-density hard disk media, non-volatile magnetic random access memory and novel magnetic logic gates that could replace volatile semiconductor logic. Compared to regular electronic devices, the magnetic devices would be faster, smaller, use less power, create less heat and they wouldn't lose information when power was turned off.
"Imagine if you never had to reboot your computer again," Rau said.
Jade Boyd | EurekAlert!
New quantum liquid crystals may play role in future of computers
21.04.2017 | California Institute of Technology
Light rays from a supernova bent by the curvature of space-time around a galaxy
21.04.2017 | Stockholm University
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
Two researchers at Heidelberg University have developed a model system that enables a better understanding of the processes in a quantum-physical experiment...
Glaciers might seem rather inhospitable environments. However, they are home to a diverse and vibrant microbial community. It’s becoming increasingly clear that they play a bigger role in the carbon cycle than previously thought.
A new study, now published in the journal Nature Geoscience, shows how microbial communities in melting glaciers contribute to the Earth’s carbon cycle, a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
21.04.2017 | Physics and Astronomy
21.04.2017 | Health and Medicine
21.04.2017 | Physics and Astronomy