Extreme magnetoresistance in magnetic rare-earth monopnictides

The acute sensitivity of the electrical resistance of certain systems to\nmagnetic fields known as extreme magnetoresistance (XMR) has recently been\nexplored in a new materials context with topological semimetals. Exemplified by\nWTe$_{2}$ and rare earth monopnictide La(Sb,Bi), these systems tend to be\nnon-magnetic, nearly compensated semimetals and represent a platform for large\nmagnetoresistance driven by intrinsic electronic structure. Here we explore\nelectronic transport in magnetic members of the latter family of semimetals and\nfind that XMR is strongly modulated by magnetic order. In particular, CeSb\nexhibits XMR in excess of $1.6 \\times 10^{6}$ % at fields of 9 T while the\nmagnetoresistance itself is non-monotonic across the various magnetic phases\nand shows a transition from negative magnetoresistance to XMR with field above\nmagnetic ordering temperature $T_{N}$. The magnitude of the XMR is larger than\nin other rare earth monopnictides including the non-magnetic members and\nfollows an non-saturating power law to fields above 30 T. We show that the\noverall response can be understood as the modulation of conductivity by the Ce\norbital state and for intermediate temperatures can be characterized by an\neffective medium model. Comparison to the orbitally quenched compound GdBi\nsupports the correlation of XMR with the onset of magnetic ordering and\ncompensation and highlights the unique combination of orbital inversion and\ntype-I magnetic ordering in CeSb in determining its large response. These\nfindings suggest a paradigm for magneto-orbital control of XMR and are relevant\nto the understanding of rare earth-based correlated topological materials.\n