Dirac semimetals are exotic quantum materials regarded as three-dimensional analogs of graphene: in such semimetals, as in graphene, the electrons behave as fermions with zero mass, leading to unique optical, magnetic, and transport properties. Only a handful of such systems, however, have been uncovered. A challenge for experimentalists lies in the often complicated electronic band structure of these materials, which makes it hard to disentangle effects due to the zero-mass relativistic electrons from those due to trivial electronic states. Now a team led by David Santos-Cottin of the University of Fribourg in Switzerland has demonstrated that a chalcogenide compound, TlBiSSe, can be synthesized with an extremely clean and tunable band structure that is characteristic of a Dirac semimetal [1]. The result suggests that TlBiSSe might be an ideal material platform for exploring relativistic-electron phenomena in solids, says Santos-Cottin.
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