Unbiased evaluation of zero-field splitting D parameter in high-spin molecules from DC magnetic data with incomplete powder averaging

A simple scheme is presented to account for preferential orientation effects in the DC magnetic response of polycrystalline samples of anisotropic high-spin molecules, like single-molecule magnets. A single additional least-squares parameter is introduced in the fitting of isothermal magnetization vs. field data to describe the leading part of a non-spherical distribution of anisotropy axes. The procedure is shown to afford an accurate D parameter and is potentially applicable whenever complete powder averaging cannot be achieved.