Powder and single crystal neutron diffraction and optical spectroscopy are used to study the effect of substituting non-magnetic (Mg2+) or magnetic (V2+, Fe2+) cations on the Cr2+ sites in the ionic ferromagnet Rb2CrCl4. Comparison of powder neutron diffraction of Rb2CrCl4 and Rb2Cr0-73Mg0-27Cl4 shows that the latter still exhibits long range order at 4·2 K with the moments parallel to the basal plane. single crystal neutron diffraction shows that substituting 11% Mg2+ lowers the Curie temperature by 19% and 3% V2+ lowers it by 6%. Analysis of satellite fine-structure near the exciton-magnon hot bands in the visible absorption spectra of crystals of Rb2CrCl4 doped with V2+ and Fe2+ leads to estimates of 6·6 K and 5·2 K for the Cr2+-V2+ and Cr2+-Fe2+ exchange constants.
Volume 134, 2022
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