Scientists Discover New Family Of Quasiparticles In Graphene-Based Materials
Arthur T Knackerbracket has found the following story:
A group of researchers led by Sir Andre Geim and Dr. Alexey Berdyugin at The University of Manchester have discovered and characterized a new family of quasiparticles named 'Brown-Zak fermions' in graphene-based superlattices.
The team achieved this breakthrough by aligning the atomic lattice of a graphene layer to that of an insulating boron nitride sheet, dramatically changing the properties of the graphene sheet.
The study follows years of successive advances in graphene-boron nitride superlattices which allowed the observation of a fractal pattern known as the Hofstadter's butterfly-and today (Friday, November 13) the researchers report another highly surprising behavior of particles in such structures under applied magnetic field.
[...] As published in Nature Communications, the work describes how electrons behave in an ultra-high-quality superlattice of graphene with a revised framework for the fractal features of the Hofstadter's butterfly. Fundamental improvements in graphene device fabrication and measurement techniques in the past decade have made this work possible.
"The concept of quasiparticles is arguably one of the most important in condensed matter physics and quantum many-body systems. It was introduced by the theoretical physicist Lev Landau in the 1940s to depict collective effects as a 'one particle excitation'," explains Julien Barrier "They are used in a number of complex systems to account for many-body effects."
[...] Julien Barrier added "The findings are important, of course for fundamental studies in electron transport, but we believe that understanding quasiparticles in novel superlattice devices under high magnetic fields can lead to the development of new electronic devices."
The high mobility means that a transistor made from such a device could operate at higher frequencies, allowing a processor made out of this material to perform more calculations per unit of time, resulting in a faster computer. Applying a magnetic field would usually scale down the mobility and make such a device unusable for certain applications. The high mobilities of Brown-Zak fermions at high magnetic fields open a new perspective for electronic devices operating under extreme conditions.
Journal Reference:
Julien Barrier, Piranavan Kumaravadivel, Roshan Krishna Kumar, et al. Long-range ballistic transport of Brown-Zak fermions in graphene superlattices [open], Nature Communications (DOI: 10.1038/s41467-020-19604-0)
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