Correlation between structure and magnetic properties in Eu\({_{1 - x}}\)Ho\({_{x}}\)CrO\({_{3}}\) (x = 0.0, 0.5 and 1.0) orthochromites

The tuning of magnetic properties in nanostructured systems by chemical substitution provides excellent opportunities to further explore new functionalities together with the involved physics. Here we present structural, microstructural and magnetic properties of Eu\({_{1-x}}\)Ho\({_{x}}\)CrO\({_{3}}\) (x = 0.0, 0.5 and 1.0) nanoparticles prepared by a combustion reaction technique. The substitution of Eu for Ho disturbs the system leading a shrinkage of the unit cell volume from 224.6(8)Å\({^{3}}\) for x = 0.0 to 218.3(8)Å\({^{3}}\) for x = 1.0, in agreement with previous results and coincident with a contraction of 3.5% of the Cr–O1–Cr bond angle as revealed by X-ray diffraction measurements. From dc magnetic susceptibility measurements, it is also observed a strong reduction of the Néel and Curie–Weiss temperatures (from T\({_{N}^{Cr}}\) = 178.0(3) K and \({\Theta _{CW}^{Cr}}\) = − 477(8) K for x = 0.0 to T\({_{N}^{Cr}}\) = 140.0(3) K and \({\Theta _{CW}^{Cr}}\) = − 22(2) K for x = 1.0) associated with the Cr\({^{3+}}\)–Cr\({^{3+}}\) interaction. Low temperature magnetization measurements (M vs H) reveal a weak ferromagnetic component as Ho enters the system suggesting alteration of the internal molecular field due to structural modifications. The structure-magnetism correlation can be explained combining Van-Vleck susceptibility, the antisymmetric exchange (Dzyaloshinskii–Moriya interaction) including the Cr–O1–Cr angle modification and the conventional Curie–Weiss analysis at high temperatures.