Amalia Coldea

Abstract:

These data are part of the manuscript (arXiv:2003.02888) entitled: "Competing pairing interactions responsible for the large upper critical field in a stoichiometric iron-based superconductor, CaKFe4As4". The data represent resistivity data collected at low temperatures and in magnetic fields up 16T using a superconducting magnet in Oxford as well as in pulsed fields up to 80T at the LNCMI in Toulouse, France. The measurements were performed between 2K and 300K either at constant temperature and varying the magnetic field or keeping the field constant and varying the temperature.

Abstract:

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 EuCd$_2$As$_2$ to be such a system. We show that Weyl nodes in EuCd$_2$As$_2$ are magnetically-induced via exchange coupling, emerging when the Eu spins are aligned by a small external magnetic field. The identification of EuCd$_2$As$_2$ 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.