In a groundbreaking study, scientists have discovered semi-Dirac fermions in the topological metal ZrSiS. For over ten years, scientists have thought about these special particles. In one direction, the particles have no mass. In another direction, they have mass. Scientists could not find them before. But now, they have detected these particles.
What are Semi-Dirac Fermions?
Semi-Dirac fermions are unique quasi particles that exhibit a hybrid dispersion relation. They behave like massless Dirac fermions in one direction and massive particles in the perpendicular direction.
This peculiar property leads to a distinctive 𝐵²/³ scaling of Landau levels. This has been observed in ZrSiS through magneto-optical spectroscopy.
What are the Landau Levels?
In quantum mechanics, we quantize the energies of cyclotron orbits of charged particles in a uniform magnetic field into discrete values, which we commonly refer to as Landau levels. Moreover, these levels are degenerate, meaning that the number of electrons per level is directly proportional to the strength of the applied magnetic field. Interestingly, Lev Landau, the Soviet physicist, is the one who inspired its name.
The Experiment
The research team, led by Yinming Shao from Columbia University, used high-field magneto-optical spectroscopy. They studied the electronic structure of ZrSiS. They observed the characteristic 𝐵²/³ power-law scaling of Landau levels, which is a fingerprint of semi-Dirac fermions. This scaling was found to be robust against material complexities and was readily identified in infrared magneto-optics experiments.
Theoretical Modeling
The team also performed ab initio calculations and theoretical modeling to pinpoint the origin of the semi-Dirac spectrum. They found that the observed semi-Dirac fermions originate from the crossing points of nodal-lines in ZrSiS. These crossing points exhibit a continuum absorption spectrum with singularities that scale as 𝐵²/³ at the crossing.
Implications
The discovery of semi-Dirac fermions in ZrSiS not only sheds light on the hidden quasi particles emerging from the intricate topology of crossing nodal-lines, but it also advances our understanding of the alluring 2D electrons present in natural bulk crystals. Furthermore, this groundbreaking discovery opens new directions for exploring correlation and topological effects in metals, thus paving the way for future research in this fascinating area.
Future Work
The research paves the way for further exploration of semi-Dirac fermions and their unique properties. Future studies could focus on the correlation and topological effects associated with these alluring particles, potentially leading to the development of new quantum materials and technologies.
For more information, refer to the original research paper here and related articles on Entech Online.
Source
Keywords: Semi-Dirac Fermions, ZrSiS, Topological Metal, Quantum Materials, Magneto-Optical Spectroscopy, Landau Levels, Nodal-Lines, Quasi particles.
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