Fig. 1

Crystal structure and magnetic field dependence of the magnetization of LaMnAsO. a LaMnAsO has the same structure as the (1111) iron-based superconductors at room temperature [12], i.e., LaFeAsO, but with Mn occupying the Fe sites. The schematic shows the ordering of the Mn magnetic moments, which are antiferromagnetically aligned in a checkerboard pattern in the ab plane, but ferromagnetically aligned along the c-axis (i.e., C-type antiferromagnet). The rectangular black boxes outline the unit cell. b Magnetic field dependence of the magnetization of LaMnAsO measured at 300 K indicates the lack of any ferromagnetic impurity, and minimal canting of the 2.4 μ_B ordered Mn moments out of the checkerboard state, during the electron microscopy experiments, which are conducted at ~2 T. F.U. in the vertical axis stands for formula unit