Effects of Cr doping on the magnetic properties of one-dimensional spin chain system α–CoV2O6

This study investigates the structural and magnetic properties of α–CoV2O6 and Cr doped α–CoV2O6 samples synthesized using a wet chemical method. X-ray diffraction (XRD) measurements and analysis indicate that α–CoV2O6 forms in a monoclinic crystal structure, with lattice parameters a = 9.26 Å, b = 3.50 Å, c = 6.62 Å, β = 111.42°, and α = γ = 90°. The magnetic properties of the compounds were probed using a vibrating sample magnetometer (VSM), by measuring the temperature, T, field, μ0H, and time, t, dependence of magnetization, M. The compounds take on an antiferromagnetic (AFM) order at 0.1 T, with an enhancement of the magnetization below 6.5 K. Cr doping resulted in an enhancement of magnetization below TN. M(μ0H) isotherms show metamagnetic transitions with a 1/3 magnetization plateau for both samples. A large hysteresis is observed for fields less than 5 T and is attributed to frozen metastable, irreversible states. M(T) data at 2.5 T and 5 T shows that the metamagnetic transitions take both compounds from an AFM to an intermediate ferrimagnetic (FI) state and ferromagnetic (FM) state at high fields. No significant changes in TN were observed with Cr doping. Zero-field-cooled (ZFC) and field-cooled (FC) bifurcation was observed for fields between 1 T and 3 T, attributed to spin-glass-like freezing of the samples at TSG. The spin-glass behaviour of the samples was confirmed using the Gabay-Toulouse (G-T) line and M(t) curves.