title: Landau quantization and quasiparticle interference in the three-dimensional Dirac semimetal Cd₃As₂.
abstract: Condensed-matter systems provide a rich setting to realize Dirac and Majorana fermionic excitations as well as the possibility to manipulate them for potential applications. It has recently been proposed that chiral, massless particles known as Weyl fermions can emerge in certain bulk materials or in topological insulator multilayers and give rise to unusual transport properties, such as charge pumping driven by a chiral anomaly. A pair of Weyl fermions protected by crystalline symmetry effectively forming a massless Dirac fermion has been predicted to appear as low-energy excitations in a number of materials termed three-dimensional Dirac semimetals. Here we report scanning tunnelling microscopy measurements at sub-kelvin temperatures and high magnetic fields on the II-V semiconductor Cd3As2. We probe this system down to atomic length scales, and show that defects mostly influence the valence band, consistent with the observation of ultrahigh-mobility carriers in the conduction band. By combining Landau level spectroscopy and quasiparticle interference, we distinguish a large spin-splitting of the conduction band in a magnetic field and its extended Dirac-like dispersion above the expected regime. A model band structure consistent with our experimental findings suggests that for a magnetic field applied along the axis of the Dirac points, Weyl fermions are the low-energy excitations in Cd3As2.
authors: 1] Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, New Jersey 08544, USA [2].
authors: Sangjun
authors: S
authors: Jeon
authors: 1] Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, New Jersey 08544, USA [2].
authors: Brian B
authors: BB
authors: Zhou
authors: Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors: Andras
authors: A
authors: Gyenis
authors: Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors: Benjamin E
authors: BE
authors: Feldman
authors: Department of Physics, University of California, Berkeley, California 09460, USA.
authors: Itamar
authors: I
authors: Kimchi
authors: Department of Physics, University of California, Berkeley, California 09460, USA.
authors: Andrew C
authors: AC
authors: Potter
authors: Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA.
authors: Quinn D
authors: QD
authors: Gibson
authors: Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA.
authors: Robert J
authors: RJ
authors: Cava
authors: Department of Physics, University of California, Berkeley, California 09460, USA.
authors: Ashvin
authors: A
authors: Vishwanath
authors: Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors: Ali
authors: A
authors: Yazdani