The influence of magnetic anisotropy on the Zeeman spectra of lanthanide doped nanoparticles

High-resolution infra-red spectra of KY3F10 nanoparticles doped with Nd3+ and Er3+ are measured in magnetic fields of up to 4T. A simple model of the magnetic splittings of the ground and excited states is used to show that the presence or absence of observable splittings depends on the anisotropy of the response to the magnetic field. Detailed crystal-field calculations accurately model the spectra, including nonlinear effects. [Display omitted] •High-resolution FTIR spectra of lanthanide-doped nanoparticles are measured.•Observable splittings depend on the anisotropy in response to a magnetic field.•A detailed crystal-field calculation successfully models the spectra.