• Letter

Single pair of Weyl nodes in the spin-canted structure of EuCd2As2

K. M. Taddei, L. Yin, L. D. Sanjeewa, Y. Li, J. Xing, C. dela Cruz, D. Phelan, A. S. Sefat, and D. S. Parker
Phys. Rev. B 105, L140401 – Published 18 April 2022
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Abstract

Time reversal symmetry breaking Weyl semimetals are unique among Weyl materials in allowing the minimal number of Weyl points, thus offering the clearest signatures of the associated physics. Here we present neutron diffraction, density-functional theory, and transport measurement results which indicate that EuCd2As2, under ambient field, strain, and pressure, is such a material with a single pair of Weyl points. Our work reveals a magnetic structure (magnetic space group C2/m) with Eu moments pointing along the [210] direction in plane and canted 30 out of plane. Density functional theory calculations using this structure show that the observed canting drastically alters the relevant electronic bands, relative to the in-plane order, leading to a single set of well-defined Weyl points. Furthermore, we find the canting angle can tune the distance of the Weyl points above the Fermi level, with the smallest distance at low canting angles. Finally, transport measurements of the anomalous Hall effect and longitudinal magnetoresistance exhibit properties indicative of a chiral anomaly, thus supporting the neutron scattering and DFT results suggesting EuCd2As2 is close to the ideal situation of the Weyl hydrogen atom.

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  • Received 11 December 2020
  • Revised 5 May 2021
  • Accepted 29 March 2022

DOI:https://doi.org/10.1103/PhysRevB.105.L140401

©2022 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

K. M. Taddei1,*,†, L. Yin2,*, L. D. Sanjeewa2,‡, Y. Li3, J. Xing2, C. dela Cruz1, D. Phelan3, A. S. Sefat2, and D. S. Parker2

  • 1Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
  • 2Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
  • 3Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA

  • *These authors contributed equally to this work.
  • Corresponding author: taddeikm@ornl.gov
  • Present address: University of Missouri Research Reactor (MURR), Columbia, Missouri 65211, USA and Department of Chemistry, University of Missouri, Columbia, Missouri 65211, USA.

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Issue

Vol. 105, Iss. 14 — 1 April 2022

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