A team of physicists say they have found a new type of quasiparticle which appears to be found in all magnetic materials, hinting that magnetism isn’t as static as we thought.
First off, what are quasiparticles? In certain systems, such as electrical circuits, quasiparticles can emerge. For instance, in lithium atoms packed together, electrons in the outer shells are able to move around to the shells of other lithium atoms, taking their negative charge with them. But the gaps themselves can be modeled as if they were particles too, with their own positive charge, moving around the system. You might think that these quasiparticles are unimportant, but they can tell us how these systems work, and are involved in everything from your electronic devices to the transfer of heat.
In a new study, researchers from the University of Missouri took a closer look at nanoscopic honeycomb-shaped neodymium (Nd) lattices with narrow structural components, discovering the new quasiparticle.
“Conventionally, domain wall kinetics is considered to be the driving mechanism behind the dynamic behavior in nanostructured magnets, which requires magnetic field or electric current application. However, at length scales approaching the single domain limit, which defines a constricted nanomagnet, the nature of magnetic interactions and the ensuing dynamic properties can change dramatically,” the team explains in their paper.
“At small single domain size length scales (∼10 nm), the competing energetics between exchange, anisotropy, and dipolar terms causes inherent fluctuations in the macroscopic magnetic correlation parameter. Consequently, a new dynamic mechanism can emerge, as evidenced by the recent numerical simulations of constricted nanomagnets using the Landau-Lifshitz magnetization model.”
The team found “vortex loop-shaped quasiparticles” existing within the structure, which exist in all magnetic materials regardless of the strength of the magnetic field, and the material’s temperature. As well as this, they found the quasiparticles to be surprisingly dynamic.
“We’ve all seen the bubbles that form in sparkling water or other carbonated drink products,” Carsten Ullrich, Curators’ Distinguished Professor of Physics and Astronomy at the University of Missouri, explained in a statement. “The quasiparticles are like those bubbles, and we found they can freely move around at remarkably fast speeds.”
These quasiparticles were subsequently found in constricted permalloy ferromagnetic nanomagnetic lattices, though the quasiparticles were more free to move around in the honeycomb structures.
“In the honeycomb structure with nanoscale elements, the quasiparticles are not tethered to ordered domains due to the restricting nature of the nanomagnetic geometry which prevents ordered [antiferromagnet] domains from growing, and as a result the quasiparticles are free to move,” the team adds in their paper.
As well as being interesting, and perhaps hinting at some deeper understanding of magnetism in general, the new quasiparticle could lead to practical uses such as creating a new generation of faster and more efficient electronics. Specifically, this could be useful in the field of spin electronics, or “spintronics“, where electron spin, rather than charge, is used to store and process information.
“The spin nature of these electrons is responsible for the magnetic phenomena,” Deepak Singh, associate professor of physics and astronomy at the university and a specialist in spintronics, added. “Electrons have two properties: a charge and a spin. So, instead of using the conventional charge, we use the rotational, or spinning, property. It’s more efficient because the spin dissipates much less energy than the charge.”
While exciting, there is a lot more to figure out before practical uses can be made of it. But for now be pleased that there is a quasiparticle that occurs in all magnetic materials, and we didn’t know about it until now.
The study is published in Physical Review Research.
Source Link: Scientists Find Surprise Vortex Loop Quasiparticles That Exist In All Magnetic Materials
