Optical, magnetic and electronic properties of Ln2O2Te (Ln = La, Sm and Gd)

The synthesis, the optical and magnetic properties and the electronic structure of the rare-earth oxytellurides of formula Ln₂O₂Te (Ln = La, Sm and Gd) are reported. The magnetic measurements show that La₂O₂Te exhibit a diamagnetic behavior. The value of the magnetization M of Gd₂TeO₂ at our highest available field (50 kOe) is about 5.5μ_B, well below the expected value for two independent Gd ions (2gJ = 14μ_B) confirming the antiferromagnetic character of this compound. The magnetic properties of Sm₂TeO₂ reveal that Sm is in its 3+ oxidation state with a large Van Vleck contribution. The electronic structure calculations, studied by means of a first principles DFT approach, are consistent with the optical measurements and suggest an indirect band gap semiconductor behavior.