Extreme Magnetoresistance in Magnetic Rare Earth Monopnictides*

The acute sensitivity of the electrical resistance to magnetic fields known as extreme magnetoresistance (XMR) has recently been explored in a new materials context with topological semimetals. Exemplified by WTe₂ and rare earth monopnictide LaSb, these semimetals tend to be non-magnetic and show XMR driven by intrinsic electronic structure. Here we explore transport in magnetic members of the latter family. In particular, we find that CeSb exhibits XMR in excess of 1.6×10⁶ % at fields of 9 T and the XMR is strongly modulated by the magneto-orbital order. The magnitude of the XMR exceeds other rare earth monopnictides and follows non-saturating power law to fields above 30 T. Comparison to the orbitally quenched GdBi highlights the unique combination of orbital inversion and type-I magnetic ordering in CeSb in determining its large response. These findings suggest a paradigm for magneto-orbital control of XMR and are relevant to the understanding of rare earth-based correlated topological materials. Reference: Arxiv/1704.04226.