Reversal magnetization and exchange bias effect of the nanocrystalline Yb 1-x Pr x CrO 3 solid solution

Polycrystalline samples of Yb 1-x Pr x CrO 3 (0 ≤ x ≤ 1) were synthesized in the whole solubility range by auto-ignition high-temperature synthesis. TEM images revealed a particle size of about 20–25 nm in the solid solution for as-combustion powders. The crystal structure and the chemical state of the cations were characterized by a combination of X-ray diffraction method and X-ray photoelectron spectroscopy. It is found a complete solubility of the Pr ions and a mixed valence state in the Yb-rich composition range (Yb 1-x Pr x CrO 3 ; 0 < x < 0.5). There, the presence of Yb 2+ ions is compensating by the Pr 4+ valence states. Besides, the spectroscopy results found a mix of Cr 3+ and Cr 6+ valence states in the solid solution. Temperature dependence of DC-magnetization measurements showed that the antiferromagnetic transition increases almost linearly from ~ 119 for YbCrO 3 to ~ 243 K for PrCrO 3 . Furthermore, the magnetization reversal observed in the YbCrO 3 is progressively weakened with increasing Pr content and disappears for x = 0.30 of Pr substitution. The isothermal magnetization measured below of T N1 and T N2 (2 K) found that the weak ferromagnetism is canceled in the YbCrO 3 magnetic ground state. Opposite to this behavior, the end PrCrO 3 composition showed a defined magnetic hysteresis loop which infers a weak ferromagnetic component in the magnetic ground state. Besides, the M–H curves showed a negative exchange bias (EB) effect induced by Pr substitution, which is observed above of x = 0.04, and being more intense for x = 0.10 of Pr composition. The vanishing magnetization reversal and exchange bias effect are influenced strongly by the weak ferromagnetic component arising from PrCrO 3 sub-lattice in solid solution. The results demonstrate once again, the importance of the interaction between Dzyaloshinsky–Moriya and single-ion anisotropy in the orthochromite family. Also, the results here could stimulate research toward understanding the magnetic ground state whose investigations below T N2 are scares in both compounds.