Spin-polarized scanning tunneling microscopy and quasiparticle interference imaging of the magnetic Weyl candidate CeBi*

A Weyl semimetal arises when a bulk Dirac point is split into two Weyl nodes by breaking inversion or time-reversal symmetry (TRS). At low T and increasing B-field, the candidate Weyl material CeBi exhibits a cascade of TRS-breaking magnetic phases. Here we focus on the ferrimagnetic and fully-polarized phases of CeBi, where our density functional theory (DFT) calculations predict several Weyl nodes near the Fermi level (EF). We use spin-polarized scanning tunneling microscopy (SP-STM) and spectroscopy to image the surface magnetic order, and quasiparticle interference (QPI) measurements to quantify the band splitting. Strong suppression of the surface spin-polarization at EF, coincident with a Fano line shape in dI/dV, suggests the Bi p states partially Kondo screen the f magnetic moments, and this p-f mixing causes strong Fermi-level band renormalization. The QPI measurements support p band flattening and ~100 meV splitting, suggesting a strongly interacting magnetic Weyl semimetal with robustly spaced nodes.