Synthesis and characterization of Ca-doped LaMnAsO

Here, we report on our attempt to hole-dope the antiferromagnetic semiconductor LaMnAsO by substitution of the La³⁺ site by Ca²⁺. We use neutron and x-ray diffraction, magnetic susceptibility, and transport techniques to characterize polycrystalline (La_1–xCa_x)MnAsO samples prepared by solid-state reaction and find that the parent compound is highly resistant to substitution with an upper limit x ≤ 0.01. Magnetic susceptibility of the parent and the x = 0.002(x_nom = 0.04) compounds indicate a negligible presence of magnetic impurities (i.e., MnO or MnAs). Rietveld analysis of neutron and x-ray diffraction data shows the preservation of both the tetragonal (P4/nmm) structure upon doping and the antiferromagnetic ordering temperature, T_N = 355 ± 5 K.