Observation of the chiral magnetic effect in ZrTe5

Qiang Li, Dmitri E. Kharzeev, 3 Cheng Zhang, Yuan Huang, I. Pletikosić, 5 A. V. Fedorov, R. D. Zhong, J. A. Schneeloch, G. D. Gu, and T. Valla Condensed Matter Physics and Materials Science Department, Brookhaven National Lab, Upton, New York 11973, USA Department of Physics, Brookhaven National Laboratory, Upton, New York 11973, USA Department of Physics and Astronomy, Stony Brook University, New York 11794-3800, USA Center for Functional Nanomaterials, Brookhaven National Lab, Upton, New York 11973, USA Department of Physics, Princeton University, Princeton, NJ 08544, USA Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA Abstract The chiral magnetic effect is the generation of electric current induced by chirality imbalance in the presence of magnetic field. It is a macroscopic manifestation of the quantum anomaly1,2 in relativistic field theory of chiral fermions (massless spin 1/2 particles with a definite projection of spin on momentum) – a dramatic phenomenon arising from a collective motion of particles and antiparticles in the Dirac sea. The recent discovery3–5 of Dirac semimetals with chiral quasi-particles opens a fascinating possibility to study this phenomenon in condensed matter experiments. Here we report on the first observation of chiral magnetic effect through the measurement of magneto-transport in zirconium pentatelluride, ZrTe5. Our angle-resolved photoemission spectroscopy experiments show that this material’s electronic structure is consistent with a 3D Dirac semimetal. We observe a large negative magnetoresistance when magnetic field is parallel with the current. The measured quadratic field dependence of the magnetoconductance is a clear indication of the chiral magnetic effect. The observed phenomenon stems from the effective transmutation of Dirac semimetal into a Weyl semimetal induced by the parallel electric and magnetic fields that represent a topologically nontrivial gauge field background.