New magnetic phenomena in vanadium hexacyanochromates

Abstract

Magnetic properties of Prussian blue analogues V III [Cr III (CN) 6 ].7H 2 O and (V IV O) 3 [Cr III (CN) 6 ] 2 .4H 2 0 are presented. M(T) dependence shows an increase of magnetisation below the paramagnetic Curie temperature T cp = 107 K and T cp = 167 K for the complexes with V IV and with V III , respectively. Both compounds are ordered ferrimagnetically below the Curie temperature T c = 53 K (V IV ) and T c = 88 K (V III ) determined by the Weiss method from M 2 vs. T dependence. Experimentally found μ s = 0. 63μ B (V IV ) and μ s = 0.91μ B (V III ) corresponds well with the theoretical one. The irreversibility in FC and ZFC magnetisation was observed. The maxima in M(T) at T max = 16 K (sample V IV ) and at T maX = 32 K (sample V III ) at H = 10 Oe shift to lower temperatures and become less pronounced at higher magnetic fields. The H-dependence T max , and bifurcation T irr suggests a cluster glass behaviour. Both samples exhibit a strong electron paramagnetic resonance signal at g(V III ) = 1.84 and g(V IV ) = 1.79 with the peak to peak linewidth ΔH pp (V III ) = 73 Oe and ΔH pp (V IV ) = 944 Oe at room temperature.