Doping-dependent orbital magnetism in Chromium pnictides

We present results for the phase diagram of the parent compound LaCrAsO under electron doping using the matrix random-phase approximation. At low doping levels, the system stabilizes an antiferromagnetic state in which different Cr sublattices carry opposite spins, consistent with experimental observations. As the doping concentration increases, a stripe-type antiferromagnetic phase becomes favored. At even higher doping, the system repeats the two former magnetic states, but with incommensurate magnetic ordering vectors. The commensurate magnetic phases are associated with more localized electrons in the Cr d 3 z 2 − r 2 orbital, whereas the incommensurate phases are linked to the d x y orbital, whose stronger overlap favors itinerant-electron magnetism. • Electron doping in LaCrAsO induces a sequence of magnetic orders tied to Fermi surface changes. • Dominant orbitals for magnetism shift from localized d 3 z 2 − r 2 at low doping to itinerant d x 2 − y 2 . • Magnetic wavectors evolve sharply with doping via Lifshitz transitions. • With doping, magnetic phases change from antiferromagnetism to stripe and spin-density-wave orders.