Robust noncoplanar magnetism in band-filling-tuned ( Nd1−xCax)2Mo2O7

Abstract

In the metallic pyrochlore ${\mathrm{Nd}}_{2}{\mathrm{Mo}}_{2}{\mathrm{O}}_{7}$, the conducting molybdenum sublattice adopts canted, yet nearly collinear, ferromagnetic order with nonzero scalar spin chirality. The chemical potential may be controlled by replacing ${\mathrm{Nd}}^{3+}$ with ${\mathrm{Ca}}^{2+}$, while introducing only minimal additional disorder to the conducting states. Here, we demonstrate the stability of the canted ferromagnetic state, including the tilting angle of molybdenum spins, in (${\mathrm{Nd}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}$)${}_{2}{\mathrm{Mo}}_{2}{\mathrm{O}}_{7}$ with $x\ensuremath{\le}0.15$ using magnetic susceptibility measurements. Mo-Mo and Mo-Nd magnetic couplings both change sign above $x=0.22$, where the canted ferromagnetic state gives way to a spin-glass metallic region. Contributions to the Curie-Weiss law from two magnetic species are separated systematically.