Physics – A Textbook Dirac Semimetal
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• Physics 16, s81
Researchers have synthesized a chalcogenide compound that has the digital construction of a great Dirac semimetal—which might facilitate the examine of this unique class of supplies.
Dirac semimetals are unique quantum supplies thought to be three-dimensional analogs of graphene: in such semimetals, as in graphene, the electrons behave as fermions with zero mass, resulting in distinctive optical, magnetic, and transport properties. Solely a handful of such methods, nonetheless, have been uncovered. A problem for experimentalists lies within the typically sophisticated digital band construction of those supplies, which makes it laborious to disentangle results as a result of zero-mass relativistic electrons from these as a consequence of trivial digital states. Now a crew led by David Santos-Cottin of the College of Fribourg in Switzerland has demonstrated {that a} chalcogenide compound, TlBiSSe, could be synthesized with a particularly clear and tunable band construction that’s attribute of a Dirac semimetal [1]. The end result means that TlBiSSe may be a great materials platform for exploring relativistic-electron phenomena in solids, says Santos-Cottin.
The weird properties of Dirac semimetals are related to Dirac cones—options within the digital construction the place the total (valence) and empty (conduction) bands are formed like two halves of a conical floor assembly at a Dirac level. The researchers decided their materials’s digital construction by measuring optical reflectivity and transmission, which probe digital transitions between the valence and conduction bands. Investigating three samples synthesized with completely different preliminary ratios of thallium to bismuth, they discovered that such ratios managed the place of the Fermi vitality—which dictates the boundary between occupied and unoccupied vitality states for electrons. For a 1.5:0.5 ratio, the pattern displayed all of the anticipated options of a Dirac semimetal: a small hole, a linear dispersion curve (plotting the connection between electron energies and momenta), and the emergence of the so-called Landau quantization of the electron vitality ranges induced by the applying of a magnetic area.
–Matteo Rini
Matteo Rini is the Editor of Physics Journal.
References
- F. Le Mardelé et al., “Proof for three-dimensional Dirac conical bands in TlBiSSe by optical and magneto-optical spectroscopy,” Phys. Rev. B 107, L241101 (2023).
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