Phys.org December 10, 2024
In two dimensions, a peculiar class of fermions that are massless in one direction and massive in the perpendicular direction was predicted 16 years ago. The semi-Dirac fermions remain undetected. An international team of researchers (USA – Columbia University, Pennsylvania State University, Florida State University, National High Magnetic Field Laboratory, Harvard University, Temple University, Princeton University, Flatiron Institute, the Netherlands, Spain) demonstrated the defining feature of semi-Dirac fermions in a prototypical nodal-line metal ZrSiS. Their nodal lines extended the band degeneracies from isolated points to lines, loops, or even chains in the momentum space. They pinpointed the observed semi-Dirac spectrum to the crossing points of nodal lines in ZrSiS. Crossing nodal lines exhibited a continuum absorption spectrum but with singularities at the crossing. According to the researchers their work sheds light on the hidden quasiparticles emerging from the intricate topology of crossing nodal lines and highlights the potential to explore quantum geometry with linear optical responses… read more. Open Access TECHNICAL ARTICLE
An illustration of the calculated structure of ZrSiS near the crossing points of its structure, showing a semi-Dirac point as a black sphere on the left… Credit:Â Physical Review X 14, 041057, 5 December, 2024