Temperature-dependent and magnetism-controlled Fermi surface changes in magnetic Weyl semimetals

Quantum oscillation measurements reveal that in magnetic Weyl semimetals NdAlSi and CeAlSi${}_{0.8}$Ge${}_{0.2}$, the areas of extremal orbits on Fermi surfaces change remarkably with varying temperature; such changes depend on the local spin configurations and magnetic-field directions. The temperature dependence of Fermi surfaces is demonstrated to be a result of the exchange coupling between the localized 4$f$ electrons and the itinerant 5$d$ electrons.