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Resonant Dynamics of Magnetic Whirls in the Spotlight

10/23/2020

Two researchers from the Materials Science and Engineering Department of the University of Illinois Urbana Champaign review the latest developments and discuss future prospects of resonant skyrmion dynamics. The Perspective article, written by Martin Lonsky, a postdoctoral researcher, and Professor Axel Hoffmann, appears in the renowned open-access journal APL Materials. It has been selected as an Editor’s Pick.

Skyrmions are tiny magnetic whirls that can occur in certain types of magnetic materials. In recent years, these objects have sparked enormous interest among scientists – not only from a fundamental research perspective, but also owing to their potential application in novel energy-efficient electronic devices and magnetic data storage technologies. In this paper, the authors review a fascinating yet marginally researched property of skyrmions and other related chiral magnetic textures: resonant dynamic excitations, which can be induced, for instance, by applying microwave magnetic or electric fields. The excited magnetization dynamics take place on nanosecond timescales, that is, on the order of a billionth of one second. An example for resonant excitations of skyrmions is given by so-called breathing modes, whereby the size of a magnetic whirl oscillates periodically with time and thus exhibits a breathing-like motion.
Schematic temporal snapshots of three characteristic skyrmion resonances, namely the breathing mode as well as the counterclockwise (CCW) and clockwise (CW) gyration modes. Red and blue colors indicate opposite directions of the out-of-plane magnetization.
Schematic temporal snapshots of three characteristic skyrmion resonances, namely the breathing mode as well as the counterclockwise (CCW) and clockwise (CW) gyration modes. Red and blue colors indicate opposite directions of the out-of-plane magnetization.

 “Most of the reported research activities on skyrmion resonance modes are theoretical. In addition to providing an overview of the most significant advances in this research field, in our article we also discuss the main obstacles towards the realization of future experiments or even technological applications and how advanced materials engineering could help to overcome these challenges,” said Martin Lonsky.

“Major challenges include too high damping of the magnetization dynamics in many materials of interest, as well as structural inhomogeneities, disorder and defects in the fabricated multilayer or thin-film samples.”

“In our research group, we are currently working intensively on the optimization of sample fabrication and characterization processes,” added Professor Axel Hoffmann. With such improvements the two researchers believe that it will be possible to provide a significant boost to experimental research on resonant skyrmion dynamics.

This work was partially supported by the NSF through the University of Illinois at Urbana-Champaign Materials Research Science and Engineering Center DMR-1720633 and was carried out in part in the Materials Research Laboratory Central Research Facilities, University of Illinois. Further support comes from the German Science Foundation.

Read the full article here: https://aip.scitation.org/doi/10.1063/5.0027042