Synthesis and structural, magnetic, thermal and electronic properties of Mn-doped ZnCr2Se4

Polycrystalline compounds of the ZnxMnyCrzSe4 system (x + y + z ≈ 3) crystallizing in a cubic spinel structure were successfully synthesized in the concentration range of x = 0.11 ÷ 0.46 using the ceramic method. The influence of manganese on microstructure, magnetic, thermal and electronic properties was investigated. X-ray studies confirmed that the spinel phase forms throughout the entire range (x = 0.1 ÷ 0.5). The results of magnetic measurements showed that the studied compounds are antiferromagnets with the Néel temperature of TN = 12 ÷ 25 K and the Curie-Weiss temperature increasing from θ = 87 K for x = 0.11 to θ = 110 K for x = 0.46. Below TN, the magnetic field dependence of magnetization shows two peculiarities at critical fields Hc1 (connected with metamagnetic threshold accompanied with transition from a helical to a conical phase) and Hc2 (where the conical magnetic structure transforms into a ferromagnetic phase). The values of Hc1 remain almost constant while the values of Hc2 shift into lower magnetic fields as the Mn content increases. These effects are interpreted in terms of the superexchange integrals for the first two coordination spheres including spin defects and non-stoichiometry. The XPS study is consistent with FPLO calculation and discerned Mn2+ charge states. The effects of different concentrations of Zn, Mn and Cr have been demonstrated by XPS experimental results. DSC/TG analysis indicates that the presence of Mn ions in the ZnCr2Se4 crystal lattice affects the stability and resistance of the doped compounds in comparison with the pure ZnCr2Se4. [Display omitted] •The semiconducting polycrystalline ZnxMnyCrzSe4 – compounds were obtained using ceramic method.•The magnetic parameters increase with increasing Mn concentration.•Magnetic studies indicated increase of the ferromagnetic component of the bond frustrated system ZnxMnyCrzSe4.•The XPS study is consistent with FPLO calculation and discerned Mn2+ charge states.•The DSC/TG measurements confirmed the thermal stability of obtained ZnxMnyCrzSe4 – compounds.