Crystal structure and magnetic property correlation in Cd1−xMxCr2Se4Cd1−xMxCr2Se4 (M=Sb, Sn, In)

• Cd1−xMxCr2Se4 with M=Sb, In, Sn have been prepared and studied for its crystal and magnetic properties.
• The substitutions bring about two effects: lattice expansion and change in the electronic charge of Cr3+ to Cr2+
• Sn-substituted compositions are reported for the first time in literature
• Lattice expansion affects the Cr–Cr and Cr–Se–Cr competing interactions
• We observe signatures in magnetic properties hinting towards low-spin transition of Cr2+

CdCr2Se4 orders magnetically below TC ∼130 K. The magnetic ordering is believed to result from strong competition between the direct Cr–Cr spin couplings and the Cr–Se–Cr exchange interactions. Partial substitution of Cd2+ by small percentage of non-magnetic In, Sb, or Sn is expected to bring about local lattice distortion and changes in the electronic charge redistribution that subtly affects the Cr–Cr and Cr–Se–Cr interactions. Our results on the measurement of magnetic properties of Cd1−xMxCr2Se4 (M=Sb, Sn, In) reflects this premise. We investigate compositions with up to 10% substitution of Cd2+ with Sb, In, and Sn ions so as to maintain the Fd3m symmetry of CdCr2Se4. The x-ray diffraction analysis using Rietveld refinement technique confirms the symmetry of the lattice and provide the various lattice parameters. Measurement of magnetic properties indicates change in the ordering temperatures and total magnetic moment. Formation of multiple Cr valence in the substituted compositions and changing lattice constant seem to effect the magnetic properties. Certain features in magnetic properties hint towards low-spin transition of Cr2+.