paper

Ultrahigh mobility and giant magnetoresistance in the Dirac semimetal CdAs

arXiv:1404.7794 · doi:10.1038/NMAT4143

Abstract

Dirac semimetals and Weyl semimetals are 3D analogs of graphene in which crystalline symmetry protects the nodes against gap formation [1-3]. NaBi and CdAs were predicted to be Dirac semimetals [4,5], and recently confirmed to be so by photoemission [6-8]. Several novel transport properties in a magnetic field have been proposed for Dirac semimetals [2,9-11]. Here we report an interesting property in CdAs that was unpredicted, namely a remarkable protection mechanism that strongly suppresses back-scattering in zero . In single crystals, the protection results in a very high mobility that exceeds cm/Vs below 4 K. Suppression of backscattering results in a transport lifetime 10 longer than the quantum lifetime. The lifting of this protection by leads to an unusual giant -linear magnetoresistance that violates Kohler's rule. We discuss how this may relate to changes to the Fermi surface induced by .

Main text has 7 pages, 4 figures and 1 table. Text has been re-written with new results added. Supplement has 8 pages, 13 figures and 1 table, Nature Materials online Nov 24, 2014

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