Abstract
Magnets, with topologically nontrivial Dirac/Weyl points, have recently attracted significant attention owing to their unconventional physical properties, such as a large anomalous Hall effect. However, they typically have a high carrier density and a complicated band structure near the Fermi energy. In this Letter, we report a degenerate magnetic semiconductor , which exhibits a single valley at the point, where field-tunable Weyl points form via a magnetic exchange interaction with the local Eu spins. By the high-field measurements on high-quality single crystals, we observed quantum oscillations in the resistivity, elastic constant, and surface impedance, which enabled us to determine the position of the Fermi energy . In combination with a first-principles calculation, we revealed that the Weyl points are located in the vicinity of when the Eu spins are fully polarized, leading to a peak of energy-dependent anomalous Hall conductivity due to the Berry curvature. Accordingly, in the forced ferromagnetic phase, we observed a large anomalous Hall effect (Hall angle ) qualitatively consistent with the calculation, which demonstrates a marked impact of the Weyl points in the simple band structure.
- Received 25 July 2022
- Revised 2 December 2022
- Accepted 8 March 2023
DOI:https://doi.org/10.1103/PhysRevB.107.L121112
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