Unraveling the structural and magnetic characteristics of Mg doped CoCr2O4

In this paper, we explore the structural and magnetic properties of Mg doped CoCr2O4 nanopowder (typical size of 10 nm) synthesized via the sol-gel auto-combustion method. X-ray diffraction, XPS, and FTIR spectra confirm spinel structure (space group Fd-3 m) with Mg2+ doped at Cr3+. Interestingly, temperature-dependent magnetizations show various magnetic transitions between 5-300 K. While they show ferrimagnetic ordering below Curie temperature of 100 K (CoCr2O4) to 80 K (CoCr1.8Mg0.2O4) samples, the irreversibility between FC and ZFC curves at blocking temperature attribute to spin blocking nature of nanoparticles. Finally, at very low temperatures (13-26 K), magnetizations again rise indicating spin-spiral transition of CoCr1.8Mg0.2O4. Furthermore, the effect of these transitions on M-H loop can be evident in terms of coercivity, saturation magnetization, and nonsaturation behavior at high magnetic fields.