Magnetic-field- and temperature-dependent fermi surface of CeBiPt

The half-Heusler compounds CeBiPt and LaBiPt are semimetals with very low charge-carrier concentrations as evidenced by Shubnikov-de Haas (SdH) and Hall-effect measurements. Neutron-scattering results reveal a simple antiferromagnetic structure in CeBiPt below T-N = 1.15 K. The band structure of CeBiPt sensitively depends on temperature, magnetic field and stoichiometry. Above a certain, sample-dependent, threshold field (B > 25T), the SdH signal disappears and the Hall coefficient reduces significantly. These effects are absent in the non-4f compound LaBiPt. Electronic-band-structure calculations can well explain the observed behaviour by a 4f-polarization-induced Fermi-surface modification.