title: Time-Reversal-Breaking Weyl Fermions in Magnetic Heusler Alloys.
abstract: Weyl fermions have recently been observed in several time-reversal-invariant semimetals and photonics materials with broken inversion symmetry. These systems are expected to have exotic transport properties such as the chiral anomaly. However, most discovered Weyl materials possess a substantial number of Weyl nodes close to the Fermi level that give rise to complicated transport properties. Here we predict, for the first time, a new family of Weyl systems defined by broken time-reversal symmetry, namely, Co-based magnetic Heusler materials XCo_{2}Z (X=IVB or VB; Z=IVA or IIIA). To search for Weyl fermions in the centrosymmetric magnetic systems, we recall an easy and practical inversion invariant, which has been calculated to be -1, guaranteeing the existence of an odd number of pairs of Weyl fermions. These materials exhibit, when alloyed, only two Weyl nodes at the Fermi level-the minimum number possible in a condensed matter system. The Weyl nodes are protected by the rotational symmetry along the magnetic axis and separated by a large distance (of order 2π) in the Brillouin zone. The corresponding Fermi arcs have been calculated as well. This discovery provides a realistic and promising platform for manipulating and studying the magnetic Weyl physics in experiments.
authors.affiliation: Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: Zhijun
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Donostia International Physics Center, P. Manuel de Lardizabal 4, 20018 Donostia-San Sebastián, Spain.|Department of Applied Physics II, Faculty of Science and Technology, University of the Basque Country UPV/EHU, Apartado 644, 48080 Bilbao, Spain.
authors.forename: M G
authors.initials: MG
authors.lastname: Vergniory
authors.affiliation: Department of Chemistry, Princeton University, Princeton, New Jersey 08540, USA.
authors.forename: S
authors.initials: S
authors.lastname: Kushwaha
authors.affiliation: Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: Max
authors.initials: M
authors.lastname: Hirschberger
authors.affiliation: Donostia International Physics Center, P. Manuel de Lardizabal 4, 20018 Donostia-San Sebastián, Spain.|Departamento de Física de Materiales, Universidad del País Vasco/Euskal Herriko Unibertsitatea UPV/EHU, 20080 Donostia-San Sebastián, Spain.|Saint Petersburg State University, 198504 Saint Petersburg, Russia.
authors.forename: E V
authors.initials: EV
authors.lastname: Chulkov
authors.affiliation: Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Ernst
authors.affiliation: Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: N P
authors.initials: NP
authors.lastname: Ong
authors.affiliation: Department of Chemistry, Princeton University, Princeton, New Jersey 08540, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Cava
authors.affiliation: Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: B Andrei
authors.initials: BA
authors.lastname: Bernevig