Structural and magnetic properties of single-crystalline spinel systems ZnCr2−x InxSe4

Abstract The single crystals of In 3+ -doped zinc chromium selenide spinel ZnCr 2 Se 4 were prepared by a chemical transport method and characterized by X-ray diffraction, magnetic measurements and ESR spectroscopy in order to examine an effect of nonmagnetic indium on the structural and magnetic properties of the system. The X-ray diffraction analysis has shown that only small amount of In entered the octahedral sites in the cubic spinel structure with space group F d 3 ¯ m . As compared with parent ZnCr 2 Se 4 , the unit cell dimensions increased slightly with increasing In content, however at the In concentration of about 10%, the structures exhibited a certain amount of octahedral vacancies. For examined compounds the Neel temperature is very similar to that of the parent spinel ZnCr 2 Se 4 , whereas the paramagnetic Curie temperature is much lower (of about 59 K) than that for matrix. It means that the frustration introduced into systems by B-sublattice indium dilution reflects the change of ferromagnetic interactions in the magnetic exchange. The temperature dependence of the ESR linewidth over region ( T / T N )>8 is interpreted by an occurrence of spin–phonon interaction. The interesting feature of the low-field magnetization is that the magnetic irreversibility observed in the separation of the FC and ZFC curves below T N is consistent with a new, weak resonance-like features.