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Polycrystalline GdCrO3 was synthesized by the solid-state reaction method. The temperature-dependent microstructure and magnetic properties were investigated systematically. Both the Raman and FTIR spectra indicate a microstructure anomaly around 170 K. Magnetic studies demonstrate that the sample experiences two magnetic transitions around TN(Cr) ~ 167 K and TN(Gd) ~ 2.8 K related to the AFM Cr3+–Cr3+ interaction and Gd3+–Gd3+ interaction. Interestingly, the ferrimagnetic interaction between Gd and Cr ions results in the temperature-dependent magnetic reversal (TMR) together with a spin flipping (SF) that occurs at Tmin ~ 25.7 K. Due to the anisotropic exchange interaction of the Gd3+–Cr3+, a spin reorientation (SR) from Г4 (Gx, Ay, Fz) phase to Г2 (Fx, Cy, Gz) phase occurs at TSR ~ 7.8 K. In addition, a giant magnetocaloric effect (MCE) caused by the second-order AFM phase transition of Gd3+ ordering is observed at T = 3 K and H = 3 T with a magnetic entropy of − ΔSM ~ 32.8 J/kg⋅K. The present research suggests that GdCrO3 can be considered as a potential candidate material for applying in magnetic refrigeration. [ABSTRACT FROM AUTHOR]

Polycrystalline GdCrO3 was synthesized by the solid-state reaction method. The temperature-dependent microstructure and magnetic properties were investigated systematically. Both the Raman and FTIR spectra indicate a microstructure anomaly around 170 K. Magnetic studies demonstrate that the sample experiences two magnetic transitions around TN(Cr) ~ 167 K and TN(Gd) ~ 2.8 K related to the AFM Cr3+–Cr3+ interaction and Gd3+–Gd3+ interaction. Interestingly, the ferrimagnetic interaction between Gd and Cr ions results in the temperature-dependent magnetic reversal (TMR) together with a spin flipping (SF) that occurs at Tmin ~ 25.7 K. Due to the anisotropic exchange interaction of the Gd3+–Cr3+, a spin reorientation (SR) from Г4 (Gx, Ay, Fz) phase to Г2 (Fx, Cy, Gz) phase occurs at TSR ~ 7.8 K. In addition, a giant magnetocaloric effect (MCE) caused by the second-order AFM phase transition of Gd3+ ordering is observed at T = 3 K and H = 3 T with a magnetic entropy of − ΔSM ~ 32.8 J/kg⋅K. The present research suggests that GdCrO3 can be considered as a potential candidate material for applying in magnetic refrigeration. [ABSTRACT FROM AUTHOR]

The Ca3CoMn1-xTixO6(x = 0, 0.05) samples were synthesized by a modified sol-gel method, and the microstructure, microtopography, and magnetic properties were investigated in detail. With substituting of Mn4+ ions by Ti4+ ions, the crystallinity and particle size of Ca3CoMn1-xTixO6 (x = 0, 0.05) samples decrease. The Ti4+ doping also causes the high-temperature spin freezing phenomenon disappears, and the transition field of ↑↑↓↓ magnetic structure to ↑↑↑↓ magnetic structure increases obviously together with the faster dynamic behavior. These results suggest that the dilution effect of Ti4+ doping to Co-Mn-Co-Mn spin chains could reduce the degree of magnetic frustration and suppress the formation of short range magnetic order, for which will be beneficial for the establishment of more robust long range antiferromagnetic structure. The present research could serve as a reference on tuning the magnetic order and improving the multiferroic property of Ca3CoMnO6. [ABSTRACT FROM AUTHOR]

• A spin glass freezing peak was observed in Ca 3 CoMnO 6 around T f = 172 K. • The results suggest the co-existence of competing short range AFM and FM order. • The short-range spin order can be suppressed effectively by external field. • Due to the competing AFM and FM interaction, exchange bias effect was observed. Rhombohedral structural Ca 3 CoMnO 6 was prepared. The microstructure, chemical composition, morphology were checked and the magnetic properties were investigated in detail. Due to the "order-by-disorder" phenomenon, the ZFC curve presents negative susceptibility in low temperature region. Besides the antiferromagnetic transition around T N = 13.5 K, another abnormal peak around T f = 172 K was also observed. The shift of the abnormal peak towards low temperature with the field increases, magnetic relaxation experiment and the training effect confirm the freezing spin glass characteristic. The broadening of the freezing peak in higher field can be well explained by the reduction of short-range magnetic correlation length. Due to the competing antiferromagnetic and ferromagnetic interactions, obvious exchange bias effect was observed. [ABSTRACT FROM AUTHOR]

In this paper, the crystal structure, vacancy defect, local electron density and magnetic properties of Gd 1- x Ca x CrO 3 (0 ≤ x ≤ 0.3) polycrystalline samples were investigated systematically. The crystal structural analyses show that all the samples are orthorhombic phase and a structural distortion happens around x = 0.3. Due to the formation of Cr4+ ions, both the lattice constant and the Cr–O bond length decrease. The results of positron annihilation spectrum reveals that the vacancy defect concentration increases and the local electron structure changes with the introduction of Ca2+ ions. The field-cooled (FC) and zero-field cooled (ZFC) curves of Gd 1- x Ca x CrO 3 samples measured under H = 100 Oe exhibits negative magnetization characteristics due to the interaction between Gd3+ and Cr3+ ions, and the magnetism can be affected by the structural distortion. [ABSTRACT FROM AUTHOR]

In this work, Ga3+ doped YCr 1- x Ga x O 3 (x = 0, 0.1, 0.2 and 0.3) polycrystalline samples were prepared by solid state reaction method and their crystal structure, morphology, internal defect, specific heat and magnetic properties were studied. The results show that the lattice constants, lattice volume and particle size increase, while Y/Cr–O bond constant decreases with replacing Cr3+ by Ga3+. The positron annihilation spectrum (PAS) measurement shows that cation vacancy defect exists in all samples and the internal defect concentration fluctuates slightly with increasing of Ga3+ ions doping concentration. For low doping content, an additional magnetization anomaly emerges in the zero-field-cooling curves measured in H = 1000Oe. With the increase of magnetic field, the anomaly can be well suppressed. Simultaneously, for the specific heat curve peak cannot be observed at the corresponding temperature. These results imply the establishment of short-range magnetic order above the antiferromagnetic transition temperature (T N) due to the dilution effect of nonmagnetic Ga3+ doping. [ABSTRACT FROM AUTHOR]

The Ca3CoMn1-xTixO6(x = 0, 0.05) samples were synthesized by a modified sol-gel method, and the microstructure, microtopography, and magnetic properties were investigated in detail. With substituting of Mn4+ ions by Ti4+ ions, the crystallinity and particle size of Ca3CoMn1-xTixO6 (x = 0, 0.05) samples decrease. The Ti4+ doping also causes the high-temperature spin freezing phenomenon disappears, and the transition field of ↑↑↓↓ magnetic structure to ↑↑↑↓ magnetic structure increases obviously together with the faster dynamic behavior. These results suggest that the dilution effect of Ti4+ doping to Co-Mn-Co-Mn spin chains could reduce the degree of magnetic frustration and suppress the formation of short range magnetic order, for which will be beneficial for the establishment of more robust long range antiferromagnetic structure. The present research could serve as a reference on tuning the magnetic order and improving the multiferroic property of Ca3CoMnO6. [ABSTRACT FROM AUTHOR]