K-State Research Team to be Featured in Applied Physics Letter journal

Kansas State University researchers predict manufacturing of smallest and thinnest swirling topological particles, called ‘2D-skyrmions’, for future secure data storage and information processing
Submitted by Suprem Das, Ph.D.

Since the invention of integrated circuits, computing is constantly revolutionizing many aspects of our day-to-day life. This is essentially possible due to the ability to place billions of transistors in a tiny area on a single computer/smartphone chip. However, the never-ending demand for such things is fast bringing the silicon technology to a dead end. This is simply because of the lack of any tiny remaining physical space in the chip and also due to no means of mitigating the heat caused by the massive number of devices, called ‘transistors’. Scientists and engineers are thus seeking for transformative ideas that could be, in the long term, the next generation of information carriers and information fundamental storage units.

One possible proposal is to use the quantum mechanical degree of freedom of an electron, called spin, instead of using the ‘charge’ in present-day electronics. Although ‘spin’ can store a massive amount of information compared to a charge, stabilizing spin and manipulating it within a material is notoriously difficult for which scientists are yet working to achieve fully.

Advanced understanding in some new materials have recently shown favorable conditions where they have shown to arrange their atomic spins in a unique and topologically protected way so that one can control these collective spins (thus called a quasi-particle, a swirling magnetic spin texture). One such topology of spins, called ‘skyrmions’, are proven to be physically stable and thus could be used as information carriers. They could also be made very small (a few tens of nanometers in size) and they are energy efficient when carrying information. So far skyrmions have been demonstrated in bulk materials and thin magnetic films when synthesized on heavy metals. Recently, in 2017, there were remarkable discoveries that showed some atomic thin materials that could be magnetic, despite a long-standing belief that argued against such theories. One such material is chromium tri-iodide, published in the journal Nature in 2017. Since late 2018, the K-State team, led by assistant professor Suprem Das, was asking the question: “If chromium tri-iodide is magnetic can there be a skyrmion in atomic thin magnet?” A concept they hypothesize as ‘2D-skyrmions’. In a recent published letter in Applied Physics Letter, they indeed showed that under certain conditions, in particular, by applying a vertical electric field to the atomic magnet one can break the symmetry of their atomic positions that sufficiently induce favorable conditions to show swirling magnetic textures, i.e., skyrmions. They used a magnetic field to see the change in the size of skyrmions, but the largest one is already below 10 nanometers in size. They used density functional theory and atomistic spin dynamics to predict topological protected structures hosted in such materials. Their work has been highlighted with a cover image in the June 2019 issue of Applied Physics Letter. Industrial Engineering graduate student Aroop Behera of Das’s research group is the first author on the research paper and the work is a collaboration with Dr. Sugata Chowdhury, senior researcher and co-author at Rice University, who is at present stationed in NIST, Gaithersburg, Maryland. The skyrmions shown by Das’ team are formed at absolute zero temperature. The path ahead will be to study them at room or near room temperatures, which the team thinks will be a significant technological achievement. The team is optimistic to hope they can study these particles at room temperatures and in atomic scale materials.