Weyl semimetals exhibit exceptional quantum electronic transport due to the presence of topologically-protected band crossings called Weyl nodes. The nodes come in pairs with opposite chirality, but their number and location in momentum space is otherwise material specific. Following the initial discoveries there is now a need for better material realizations, ideally comprising a single pair of Weyl nodes located at or very close to the Fermi level and in an energy window free from other overlapping bands. Here we propose the layered intermetallic EuCd2As2 to be such a system. We show that Weyl nodes in EuCd2As2 are magnetically-induced via exchange coupling, emerging when the Eu spins are aligned by a small external magnetic field. The identification of EuCd2As2 as a model magnetic Weyl semimetal, evidenced here by ab initio calculations, photoemission spectroscopy, quantum oscillations and anomalous Hall transport measurements, opens the door to fundamental tests of Weyl physics.
@article{arxiv.1901.10022,
title = {An ideal Weyl semimetal induced by magnetic exchange},
author = {J. -R. Soh and F. de Juan and M. G. Vergniory and N. B. M. Schröter and M. C. Rahn and D. Y. Yan and J. Jiang and M. Bristow and P. Reiss and J. N. Blandy and Y. F. Guo and Y. G. Shi and T. K. Kim and A. McCollam and S. H. Simon and Y. Chen and A. I. Coldea and A. T. Boothroyd},
journal= {arXiv preprint arXiv:1901.10022},
year = {2019}
}