In a three-dimensional magnetic insulator, delimited magnetic “hedgehogs” and “anti-hedgehogs” move in the opposite direction, resulting in a pure “hedgehog” current that can be transported over long distances. This was reported in the journal Physical Review Letters.
Spintronics is a new area of scientific research aimed at developing devices that transmit, process, and store information using the intrinsic angular momentum of electrons, known as spin. A key goal of spintronic research is to identify strategies for using magnetic isolators to transmit signals over long distances.
In turn, magnetic insulators are a class of materials widely used all over the world, mainly due to their ability to conduct electrical charges. Just as metals conduct electrical charges, magnetic insulators can conduct spins. However, since spins are rarely conserved in materials and tend to disappear at large distances, until now, using magnetic insulators to achieve long-range transport seemed to be a challenge.
Researchers recently demonstrated long-range transport of magnetic “hedgehogs,” three-dimensional topological spin structures that are often seen in conventional magnets. The results of the research carried out will find application in the development of devices that support the ideas of spintronics.
“Our idea is to use topological spin textures, rather than the spins themselves, for long-range transport,” said Shu Zhang, one of the researchers. – Magnetic “hedgehog” – one of the types of topologically protected spin texture, which usually exists in three-dimensional magnets. Our work shows that the “hedgehog” current is a well-conserved quantity and can be investigated to achieve long-range transport in magnetic insulators.”
The research by Zhang and her colleagues is based on a theoretical postulate known as topological conservation law, which allowed researchers to exploit the hydrodynamics of topological spin textures. This idea was previously explored in a series of studies led by physicist Yaroslav Tserkovnyak.
“The main theoretical approach that we applied in our research is classical field theory,” explained Zhang. We describe the space-time distribution of spins as a continuous vector field, over which topological textures and their currents can be determined and studied. The mathematical description of “hedgehog” currents is subject to the principles of the theory of electromagnetism.”
The researchers used an experimental setup in which a hedgehog current is injected and detected using metal contacts attached to the two ends of a magnet. In this scenario, the magnet could be viewed as a conductor carrying the current of topological spin textures with finite conductivity. This concept opens up huge potential for the use of magnetic insulators for long distance transportation.