Observation of three-dimensional massless Kane fermions in a zinc-blende crystal

Milan Orlita (1) , D. M. Basko (2) , Maksim Zholudev (3) , Frederic Teppe (3) , Wojciech Knap (3) , V.I. Gavrilenko (4) , N.N. Mikhailov (5) , S.A. Dvoretskii (5) , P. Neugebauer (1) , Clément Faugeras (1) , Anne-Laure Barra (1) , Gines Martinez Garcia , Marek Potemski (1)

1 LNCMI-G - Laboratoire national des champs magnétiques intenses - Grenoble
2 LPM2C - Laboratoire de physique et modélisation des milieux condensés
3 L2C - Laboratoire Charles Coulomb
4 Institute for Physics of Microstructures of the RAS
5 Institute of semiconductor Physics

Solid-state physics and quantum electrodynamics, with its ultrarelativistic (massless) particles, meet in the electronic properties of one-dimensional carbon nanotubes, two-dimensional graphene or topological-insulator surfaces. However, clear experimental evidence for electronic states with a conical dispersion relation in all three dimensions, conceivable for certain bulk materials, is still missing. Here, we study a zinc-blende crystal, HgCdTe, at the point of the semiconductor-to-semimetal topological transition. For this compound, we observe three-dimensional massless electrons, as certified from the dynamical conductivity increasing linearly with the photon frequency, with a velocity of about 106 m s−1. Applying a magnetic field B results in a -dependence of dipole-active inter-Landau-level resonances and spin splitting of Landau levels also following a -dependence--well-established signatures of ultrarelativistic particles but until now not observed experimentally in any solid-state electronic system.

Domaines: Agrégats Moléculaires et Atomiques [physics.atm-clus]

Milan Orlita, D. M. Basko, Maksim Zholudev, Frederic Teppe, Wojciech Knap, et al.. Observation of three-dimensional massless Kane fermions in a zinc-blende crystal. Nature Physics, 2014, 10 (3), pp.233-238. ⟨10.1038/nphys2857⟩. ⟨hal-00973456⟩