Structural and magnetic properties of CuCr 2 Se 4 single crystals diluted with Sb(III)

A series of single crystals based on CuCr2Se4 spinel diluted with Sb ions was prepared by chemical vapour transport. They were characterized by X-ray fluorescent spectroscopy (XRF), X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and bulk magnetization measurements. The results revealed that nonmagnetic Sb3+ ions substitute Cr3+ ions at the octahedral sites. For the Sb3+ content x=0.06 the single crystals of (Cu)[Cr2−xSbx]Se4 were formed, while for larger Sb concentration (x=0.12 and x=0.16) the crystals with cation vacancies at the octahedral sites were obtained. The XPS data evidenced the 3d3 electronic configuration of Cr ions with localized magnetic moments for the three compositions differing in the Sb content. Despite the unaltered valence state of Cr ions along the series, the low-temperature magnetic characteristics have changed considerably. With increasing content of Sb the saturation magnetic moment was found to radically decrease. This effect may be explained in terms of the perturbation in the ferromagnetic Cr–Se–Cr indirect exchange interactions caused by the presence of increasing number of dopant atoms and vacancies in the crystal lattice.