Crystal field effect on the effective magnetic moment in A2CoWO6 (A = Ca, Sr and Ba)

We prepared the antiferromagnetic Ca2CoWO6, Sr2CoWO6 and Ba2CoWO6 double perovskites with different crystalline structures, which are monoclinic, tetragonal and cubic respectively. The crystalline structures affect the Co–O distances and the local octahedral symmetry. Magnetic susceptibility experiments were performed as a function of magnetic field and temperature. We found that the effective magnetic moment (μeff) of Co2+ is partially unquenched and we also found that μeff increases with the average of Co–O distances that form the CoO6 octahedra. A simple model associates the behavior of the effective magnetic moment with crystal field effects.

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► Ca2CoWO6, Sr2CoWO6 and Ba2CoWO6 are monoclinic, tetragonal and cubic.
► The crystalline structure affects the Co–O distances.
► Effective magnetic moment (μeff) of Co2+ is partially unquenched.
► The μeff value increases with the Co–O distances.
► The μeff temperature dependence is explained with axial distortion of the crystal field effect.