“Antiferromagnets have the potential to out-compete other forms of memory, which would lead to a redesign of computing architecture, huge speed increases and energy savings. The additional computing power could have large societal impact. These findings are really exciting, as they bring us closer to realizing the potential of antiferromagnet materials to transform the digital landscape.”Peter Wadley, University of Nottingham
A new study has demonstrated for the first time how the electrical creation and control of magnetic vortices in an antiferromagnet can be achieved. This discovery could help increase the data-storage capacity and speed of next-generation devices.
Researchers from the School of Physics and Astronomy at the University of Nottingham in the UK used magnetic imaging techniques to map the structure of newly formed magnetic vortices in an antiferromagnet and to demonstrate their back-and-forth movement due to alternating electrical pulses. They report their findings in a paper in Nature Nanotechnology.
“This is an exciting moment for us; these magnetic vortices have been proposed as information carriers in next-generation memory devices, but evidence of their existence in antiferromagnets has so far been scarce,” says Oliver Amin, a research fellow at the University of Nottingham and lead author of the paper. “Now, we have not only generated them, but also moved them in a controllable way. It’s another success for our material, CuMnAs, which has been at the center of several breakthroughs in antiferromagnetic spintronics over the last few years.”
CuMnAs is a compound of copper, manganese and arsenic with a specific crystal structure. It is grown in an almost complete vacuum, atomic layer by atomic layer, and has been shown to behave like a switch when pulsed with electrical currents. The research group in Nottingham, led by Peter Wadley, alongside international collaborators, has ‘zoomed in’ on the magnetic textures in this antiferromagnet: first with a demonstration of moving domain walls, and now with the generation and control of magnetic vortices.
Key to this research is a magnetic imaging technique called photoemission electron microscopy, which was carried out at the UK's synchrotron facility, Diamond Light Source. The synchrotron produces a collimated beam of polarized X-rays, which is shone onto the sample to probe its magnetic state. This allows for a spatial resolution of micromagnetic textures down to 20nm.
Magnetic materials have been technologically important for centuries, from the compass to modern hard disks. However almost all of these materials have belonged to one type of magnetic order – ferromagnetism. This is the type of magnet we are all familiar with, from fridge magnets to washing machine motors to computer hard disks. They produce an external magnetic field that we can ‘feel’ because all the tiny atomic magnetic moments that constitute them like to align in the same direction. It is this field that causes fridge magnets to stick and that we sometimes see mapped out with iron filings.
Because they lack an external magnetic field, antiferromagnets are hard to detect and, until recently, hard to control. For this reason, they have found almost no applications. Antiferromagnets produce no external magnetic field because all of the neighboring constituent tiny atomic moments point in opposite directions to each other. In doing so they cancel each other out and so no external magnetic field is produced: they won't stick to fridges or deflect a compass needle.
But antiferromagnets are magnetically more robust and the movement of their tiny atomic moments happens approximately 1000 times faster than in a ferromagnet. They could thus form the basis for computer memory that operates far faster than current memory technology.
“Antiferromagnets have the potential to out-compete other forms of memory, which would lead to a redesign of computing architecture, huge speed increases and energy savings,” says Wadley. “The additional computing power could have large societal impact. These findings are really exciting, as they bring us closer to realizing the potential of antiferromagnet materials to transform the digital landscape.”
This story is adapted from material from the University of Nottingham, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.