Weak Ferromagnetic Transition Research Articles

Effect of Mg doping at Fe/Cr site on magnetic and optical properties of Gd2FeCrO6 double perovskite

The influence of Mg doping on structural, magnetic and optical characteristics of Gd2FeCrO6, Gd2Fe0.75Mg0.25CrO6 and Gd2FeCr0.75Mg0.25O6 double perovskites has been systematically investigated. The monoclinic crystal structure with the P21/n space group is confirmed by powder X-ray diffraction data. From the scanning electron microscopy graphs, we noticed few nearly spherical and dumbbell-shaped grains for all compounds with an average grain size of about 76 - 85 nm. The magnetic studies demonstrated the presence of a weak ferromagnetic transition with antiferromagnetic background at low temperatures for all the samples. A decrement in the transition temperature of Gd2FeCrO6 (TC = 8.14 K) is observed on Mg doping, which is due to the smaller ionic radii of Mg at the Fe/Cr site in Gd2Fe0.75Mg0.25CrO6 and Gd2FeCr0.75Mg0.25O6 double perovskites. By analyzing the UV–visible spectroscopic absorption data, direct band gaps around 3 eV are concluded for pure and Mg doped Gd2FeCrO6 double perovskites, validating their application in wastewater photocatalysis.

Growth of millimeter-sized high-quality CuFeSe2 single crystals by the molten salt method and study of their semiconducting behavior

An eutectic AlCl3/KCl molten salt method in a horizontal configuration was employed to grow millimeter-sized and composition homogeneous CuFeSe2 single crystals due to the continuous growth process in a temperature gradient induced solution convection. The typical as-grown CuFeSe2 single crystals in cubic forms are nearly 1.6 × 1.2 × 1.0 mm3 in size. The chemical composition and homogeneity of the crystals was examined by both inductively coupled plasma atomic emission spectroscopy and energy dispersive spectrometer with Cu:Fe:Se = 0.96:1.00:1.99 consistent with the stoichiometric composition of CuFeSe2. The magnetic measurements suggest a ferrimagnetic or weak ferromagnetic transition below TC = 146 K and the resistivity reveals a semiconducting behavior and an abrupt increase below TC.

Structural, magnetic and magnetocaloric effect of pyrochlore iridate Er2Ir2O7

The structural, morphological, magnetic and magnetocaloric properties of Er2Ir2O7 are investigated. The x-ray diffraction analysis showed that Er2Ir2O7 has a cubic structure with the Fđ3m space group. Using Williamson-Hall (W-H) plot, the crystallite size was found to be smaller than that obtained from the SEM image. Magnetic measurements revealed a weak ferromagnetic transition at TC = 140 K, caused by the appearance of magnetic order of the Ir moments. ΔT (temperature at full width of half maxima) was estimated to be 27 K and 40 K for magnetic field changes of 40 kOe and 50 kOe, corresponding to the relative cooling power (RCP) values of 98 J kg−1 and 128 J kg−1, respectively. Temperature-averaged Entropy Change (TEC) was calculated for all applied magnetic fields, and found to be slightly lower than values, indicating less hysteresis loss in the compound Er2Ir2O7 during the magnetic transition. This study provides a new pyrochlore material for MCE magnetocaloric applications.

Crystallite size-dependent magnetic moment in hydrogen bridged manganese tetracyanonickelate based two-dimensional metal-organic frameworks

Two-dimensional (2D) metal–organic frameworks (MOFs) are the coordination network of organic cyanide (CN) ligands and metal cyanometallates. They possess great potential as molecular magnets between subzero up to above room temperature. These complexes are greatly sought after due to the unique structural features that allow them to offer tunable magnetic properties by changing crystal entities and/or through external stimulation such as light and heat. Layered structure of tetracyanonickellate based MOFs T(H2O)2Ni(CN)4·.4H2O, T = Mn herein called Mn-MOF, have been synthesized by the chemical precipitation method with controlled particle size using tri-sodium citrate dihydrate (TSCD) as the chelating agent. This work involves the study of spontaneous magnetism in the layered solid, the effect of their crystallite sizes and morphology on the magnetic susceptibility. The magnetic interaction takes place in-plane between the pseudo-octahedral metal (T) ions through the diamagnetic Ni2+ center, and out-of-plane through the hydrogen bonding bridge formed in the interlayer spacing. Magnetic properties were measured using Vibrating Sample Magnetometry (VSM) and calculated for Curie temperatures with magnetic exchange energies using the Curie-Weiss mean field theory and total angular momentum of the involved metal ions. The MOFs exhibit a paramagnetic behavior above 50 K and show increased magnetic susceptibility on cooling with a paramagnetic to weak ferromagnetic (wFM) transition below 50 K. A field-dependent response of the magnetic ordering temperature from 34 to 44 K was also observed for the Mn(H2O)2Ni(CN)4·.4H2O complex. The value of magnetic exchange coupling between interlayer metal centers increases though the hydrogen bonding network which results increased magnetic moment with decreased crystallite surface area to volume ratio.

Effect of magnetic phase coexistence on spin-phonon coupling and magnetoelectric effect in polycrystalline Sm0.5Y0.5Fe0.58Mn0.42O3

The various physical properties with their intercorrelations in polycrystalline samples of Sm0.5Y0.5Fe0.58Mn0.42O3 [SYFM (58–42)] were investigated. The dc magnetization measurements revealed a weak ferromagnetic (WFM) transition at TÑ361 K that is followed by an incomplete spin reorientation (SR) transition at TSR1∼ 348 K. A first order magnetic transition (FOMT) around TSR2 ∼ 292 K completes the spin reorientation transition and the material enters into a nearly collinear antiferromagnetic (AFM) state. Robust magnetodielectric (MD) is found to be present in material at room temperature. True ferroelectric transition with TFE = 108 K and having a value of saturation polarization (∼0.06 μC/cm2 at 15 K) have been found in the specimen. This spin phonon coupling (SPC) stabilizes the ferroelectric state and responsible for magnetoelectric coupling (ME). We argue that wave vector (q) dependence of the spin-pair correlation affects the electronic and magnetodielectric properties in a similar way.

Mn2−xHoxSnS4: A mixed quaternary metal chalcogenide system with an antiferromagnetic ordering

Mn2SnS4 is a unique compound in the category of MII2AIVQ4 (M ​= ​3d metal, A ​= ​Gr 14 element and Q ​= ​S, Se and Te) with distinct crystal structure as well as magnetic properties. In this research article, we report synthesis and study of magnetic properties of holmium substituted (up to 10%) Mn2SnS4 compounds. From the Rietveld refinement of powder X-ray diffraction data, it is observed that Ho preferentially occupies Mn-site and there is no site disorder at Sn position. XPS study indicate that Mn, Ho and S adopt ​+ ​II, +III and –II oxidation state, respectively. To facilitate the aliovalent substitution (Ho3+ in place of Mn2+), tin adopt mixed valence, a mixture of +IV and +II state (i.e., Sn4+/Sn2+) and maintain the charge neutrality. Parent Mn2SnS4 is an antiferromagnetic compound with two magnetic transitions: i] 53 ​K (a probable spin canting induced weak ferromagnetic transition) and ii] 152 ​K (an ordered antiferromagnetic transition). Upon holmium substitution, the low temperature magnetic transition completely disappears, however, the high temperature antiferromagnetic transition is retained with ordering temperature around 150 ​K.

Crystal growth and magnetic properties of LaMn0.91Sb2 and NdMn0.88Sb2

In this work, single crystals of ${\mathrm{LaMn}}_{0.91}{\mathrm{Sb}}_{2}$ and ${\mathrm{NdMn}}_{0.88}{\mathrm{Sb}}_{2}$ with deficiencies of Mn have been successively grown by using the Bi-flux method. They all crystallize in the ${\mathrm{HfCuSi}}_{2}$-type tetragonal structure with space group $P4$/nmm (No.129). ${\mathrm{LaMn}}_{0.91}{\mathrm{Sb}}_{2}$ displays signs of successive antiferromagnetic transitions around 133 and 108 K for $H||c$. In the case of $H\ensuremath{\perp}c$, ${\mathrm{LaMn}}_{0.91}{\mathrm{Sb}}_{2}$ shows signs of weak ferromagnetic transition around 138 K and antiferromagnetic transition at 56 K. However, there is no anomaly observed in the temperature-dependent specific heat curve. For ${\mathrm{NdMn}}_{0.88}{\mathrm{Sb}}_{2}$ measured with $H||c$, the Mn sublattice orders antiferromagnetically below 170 K and the Nd sublattice shows successive antiferromagnetic orders at 34 and 26 K. The antiferromagnetic state of Nd sublattice can be induced to be a ferromagnetic state through a spin-flop transition at 2 K. When $H\ensuremath{\perp}\mathrm{c}$, the Mn sublattice displays antiferromagnetic orders at 171, 156, and 74 K. The Nd sublattice orders antiferromagnetically below 32 K. Ferromagnetic state for the Nd sublattice is induced by magnetic fields through a spin-flop transition at 2 K. Magnetic phase diagrams for ${\mathrm{NdMn}}_{0.88}{\mathrm{Sb}}_{2}$ are depicted for cases of $H||c$ and $H\ensuremath{\perp}c$, respectively. ${\mathrm{LaMn}}_{0.91}{\mathrm{Sb}}_{2}$ and ${\mathrm{NdMn}}_{0.88}{\mathrm{Sb}}_{2}$ show metallic behavior. Negative magnetoresistance in ${\mathrm{LaMn}}_{0.91}{\mathrm{Sb}}_{2}$ and ${\mathrm{NdMn}}_{0.88}{\mathrm{Sb}}_{2}$ are possibly related to canted-antiferromagnetic orders of Mn sublattices.

Flux Method Growth and Structure and Properties Characterization of Rare-Earth Iron Oxides Lu1−xScxFeO3 Single Crystals

Perovskite rare-earth ferrites (REFeO3) have attracted great attention for their high ferroelectric and magnetic transition temperatures, strong magnetoelectric coupling, and electric polarization. We report on the flux method growth of rare-earth iron oxide Lu1−xScxFeO3 single crystals through a K2CO3-B2O3-Bi2O3 mixture as a flux solution, and give a detailed characterization of the microstructure, magnetism, and ferroelectric properties. X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX) measurements revealed that the obtained single crystals can be designated to three different crystal structures of different chemical compositions, that is, Lu0.96Sc0.04FeO3 (perovskite phase), Lu0.67Sc0.33FeO3 (hexagonal phase), and Lu0.2Sc0.8FeO3 (bixbyite phase), respectively. Magnetic measurements indicate that the perovskite Lu0.96Sc0.04FeO3 is an anisotropic hard ferromagnetic material with a high Curie transition temperature, the bixbyite Lu0.2Sc0.8FeO3 is a low temperature soft ferromagnetic material, and the hexagonal Lu0.67Sc0.33FeO3 exhibits multiferroic properties. Lu0.67Sc0.33FeO3 possesses a weak ferromagnetic transition at about 162 K. We further investigate the ferroelectric domain structures in hexagonal sample by scanning electron microscope and the characteristic atomic structures in ferroelectric domain walls by atomically resolved scanning transmission electron microscope. Our successful growth of perovskite Lu1−xScxFeO3 single crystals with distinct crystal structures and stochiometric Lu-Sc substitutions is anticipated to provide a useful ferrites system for furthering exploitation of their multiferroic properties and functionalities.

Successive weak-ferromagnetic transitions in α-Sm2S3

Magnetization and specific heat have been investigated for a single crystal and a sintered sample of α-Sm2S3 having an orthorhombic crystal structure. The weak-ferromagnetic transitions have been found and the Curie temperatures are determined as TC1 = 3.6 K and TC2 = 1.8 K from the magnetic specific heat Cmag(T) of a single crystal under no magnetic field. The weak-ferromagnetic features are extremely anisotropic, and the easy-magnetization axis is c which is perpendicular to the longitudinal direction of the needle-like single crystal. The saturation magnetization at T = 2.0 K and H = 100 Oe along the c-axis after field-cooling (FC) is so small as 1/18 of the full moment of Sm3+. The magnetization M(T) after zero-field cooling (ZFC) shows a curious peak at about 4.5 K just above TC1 regardless of the direction of the applied magnetic field for the single crystal. While both M(T) curves of FC/ZFC for the sintered sample show such peaks at about 4.0 K. The Cmag(T) behaves characteristically depending on the direction of the applied magnetic field. The magnetic entropy Smag(T) is also extremely anisotropic for the magnetic-field direction, and the Smag(T) under H//a is almost invariant to the field within 70 kOe. Therefore, it might be useable for controlling MCE effect by its rotating in magnetic field.

Polaron hopping conduction mechanism and magnetic properties of Pb‐doped LaMnO3

AbstractIn the present work, we have synthesized La1‐xPbxMno3 (0 ≤ x ≤ 0.20) perovskites through a conventional solid‐state reaction route. The powder x‐ray diffraction data analyzed through the Rietveld refinement program confirm monophase rhombohedral distorted structure (R‐3c space group). Fourier transform infrared spectra exhibit strong and well‐defined absorption bands of a typical perovskite structure. The x‐ray photoelectron spectroscopy studies confirm the elemental composition and oxidation state of various elements in the samples. Low temperature resistivity measurements do not reveal metal–semiconductor transition (MST) in the pristine sample while Pb‐doped samples show MST. The metallic region of the temperature‐dependent resistivity data is well fitted with ρ(T) = ρο + ρ2.5T2.5, which reveals the significance of electron–magnon interaction. Moreover, the semiconducting behavior of all the samples follows the Mott's variable range hopping conduction process. Additionally, the semiconducting part is also fitted with the small‐polaron hopping (SPH) model that establishes the non‐adiabatic SPH mechanism obeyed for the lower doping, whereas adiabatic mechanism for the higher Pb concentration. Magnetic studies clearly indicate a paramagnetic to weak ferromagnetic transition associated with the Pb doping that may be due to the double‐exchange mechanism between the manganese ions via oxygen orbitals. The outcomes are elucidated on the basis of substitution effect induced by Pb2+ ions.

Large Anisotropic Magnetocaloric Effect, Wide Operating Temperature Range, and Large Refrigeration Capacity in Single-Crystal Mn5Ge3 and Mn5Ge3/Mn3.5Fe1.5Ge3 Heterostructures.

At present, the studies on magnetocaloric properties are mainly based on polycrystalline materials, which is not enough to reveal and understand the origin of their magnetocaloric effect. In addition, finding new room temperature magnetocaloric materials is crucial to the development and application for room temperature magnetic refrigeration. Here, we report the magnetic transitions, magnetic anisotropy, and magnetocaloric properties of single-crystal Mn5Ge3 and Mn5Ge3/Mn3.5Fe1.5Ge3 heterostructures with six (100) surfaces and the [001] growth direction prepared using the Sn flux method. Mn5Ge3 (Mn3.5Fe1.5Ge3) undergoes a sharp paramagnetic-collinear ferromagnetic transition at 299 (332) K and weak collinear-noncollinear ferromagnetic transition at 65 (35) K. Owing to the distinct spin arrangements and magnetic moments of Mn5Ge3 and Mn3.5Fe1.5Ge3, the magnetic anisotropy of the single crystal is stronger than that of the heterostructure below 299 K. Moreover, a large anisotropic magnetocaloric effect, wide operating temperature range, and large refrigeration capacity near room temperature are obtained in these two materials, especially the magnetocaloric effect of the heterostructure presents a tablelike shape due to the adjacent paramagnetic-collinear ferromagnetic transitions of Mn5Ge3 and Mn3.5Fe1.5Ge3. Under 0-3 T, the maximum magnetic entropy change, operating temperature range, and refrigeration capacity of the single crystal (heterostructure) are 5.19 (2.96) J kg-1 K-1, 43 (57) K, and 223 (169) J kg-1 when H//c, respectively. These features make them candidates for room temperature magnetic refrigeration.

Observation of novel charge ordering and spin reorientation in perovskite oxide PbFeO3

PbMO3 (M = 3d transition metals) family shows systematic variations in charge distribution and intriguing physical properties due to its delicate energy balance between Pb 6s and transition metal 3d orbitals. However, the detailed structure and physical properties of PbFeO3 remain unclear. Herein, we reveal that PbFeO3 crystallizes into an unusual 2ap × 6ap × 2ap orthorhombic perovskite super unit cell with space group Cmcm. The distinctive crystal construction and valence distribution of Pb2+0.5Pb4+0.5FeO3 lead to a long range charge ordering of the -A-B-B- type of the layers with two different oxidation states of Pb (Pb2+ and Pb4+) in them. A weak ferromagnetic transition with canted antiferromagnetic spins along the a-axis is found to occur at 600 K. In addition, decreasing the temperature causes a spin reorientation transition towards a collinear antiferromagnetic structure with spin moments along the b-axis near 418 K. Our theoretical investigations reveal that the peculiar charge ordering of Pb generates two Fe3+ magnetic sublattices with competing anisotropic energies, giving rise to the spin reorientation at such a high critical temperature.

The structure, vacancy characteristics, and magnetic properties of GdMn1-xCrxO3 ceramics

To investigate the evolution of the structural and enhanced magnetic properties of GdMnO3 systems induced by the substitution of Mn with Cr, polycrystalline GdMn1-xCrxO3 samples were synthesized via solid-state reactions. XRD characterization shows that all GdMn1-xCrxO3 compounds with single-phase structures crystallize well and that Cr3+ ions entering the lattice sites of GdMnO3 induce structural distortion. SEM results indicate that the grain size of the synthesized samples (a few microns) decreases as the Cr substitution concentration increases. Positron annihilation lifetime spectroscopy reveals that vacancy-type defects occur in GdMn1-xCrxO3 ceramics and that the vacancy size and concentration clearly change with the Cr content. The temperature and field dependence of the magnetization curves show that Cr substitution significantly influences the magnetic ordering of the gadolinium sublattice, improving the weak ferromagnetic transition temperature and magnetization of GdMn1-xCrxO3. The enhanced magnetization of GdMn1-xCrxO3 is closely related to the vacancy defect concentration.

Enhanced high temperature ferromagnetism in Bi1−x R x FeO3 (R = Dy, Y) compounds

In this work we report experimental evidence for the weak high-temperature ferromagnetism in Bi1−x R x FeO3 (R = Dy, Y) compounds by systematic characterizations, excluding the possible side-effects from other iron-based impurities. Remarkable saturated magnetic moment was observed in the Y-substituted samples, Bi1−x Y x FeO3, which is larger than the moment obtained in Bi1−x Dy x FeO3, the Dy-substituted samples with antiferromagnetic background. The physical origin of the weak ferromagnetic transition is discussed and serious lattice distortions have been identified based on the x-ray diffraction and Raman scattering data, although the rhombohedral structure symmetry remains unchanged upon the substitutions. It is believed that the structural distortion suppressed cycloid spin structure is the main factor for the enhanced magnetization in Bi1−x R x FeO3 compounds. Additionally, the Dy3+–Fe3+ antiferromagnetic coupling, which strengthens the antiferromagnetic interaction in Bi1−x Dy x FeO3 compounds, acts as the driving force for the magnetic discrepancy between Bi1−x Y x FeO3 and Bi1−x Dy x FeO3 samples.

Effect of Mg doping on the improvement of photoluminescence and magnetic properties of NiO nanoparticles

NiO nanoparticles doped with different concentration of Mg were synthesized by a low cost wet chemical method. XRD characterization indicated that the fcc structure of NiO is not affected with Mg doping. TEM analysis further reveals the Mg doping induced reduction in grain agglomeration along with the spherical shape transformation in NiO. Significant enhancement of UV emission in Mg doped NiO nanoparticles is evident from photoluminescence characterization. Magnetic characterization of the samples showed that all the samples show weak ferromagnetism along with the dominance of background antiferromagnetism at room temperature. The perseverance of background antiferromagnetic order is further probed through Raman characterization. All the samples show first order antiferromagnetic to weak ferromagnetic transition along with the presence of shape memory effect as evident by the negative slope in Arrott plot. The Ni0.9Mg0.1O sample with much enhanced UV emission and magnetization could find the usefulness in UV optoelectronic device, spintronic device etc.

Re-entrant spin-glass behavior induced by co-doping in hexagonal Y0.3Lu0.7MnO3 single crystal

Abstract The crystal structure and magnetic properties of hexagonal Y0.3Lu0.7MnO3 single crystal have been systematically investigated. The refinement results of X-ray diffraction pattern reveal that pure sample with single phase exhibits hexagonal structure with P63cm space group. Upon cooling, it undergoes multiple magnetic phase transitions, including antiferromagnetic, weak ferromagnetic, and spin-glass transitions. The spin glass at low temperature is not conventional but has a re-entrant character. We propose that the re-entrant spin-glass behavior comes from the competition between the ferromagnetic and antiferromagnetic interactions, and the disorder induced by Lu dopant, which are two characteristics of spin glass. Our study on Y0.3Lu0.7MnO3 single crystal would help people better understand the physical properties of the doped manganite compounds R1-xAxMnO3.

Magnetothermodynamic properties of frustrated pyrochlore Gd2FeSbO7 in cooperative two-sublattice molecular-field model

The pyrochlore, Gd2FeSbO7, having general formula unit A2B2O7, was chosen for magnetic and heat capacity study in this work due to presence of Fe3+ moments, whose 3d orbitals (3d5:3t2g3eg2) are half-filled and carry a large magnetic moment, at B site of the structure, and hence create additional Gd−O−Fe−O−Gd pathways, which result in strongly antiferromagnetic superexchange interactions among the Gd−Gd spins as well as for the Gd−Fe bonds. Gd2FeSbO7 behaves paramagnetic down to ~10 K with effective antiferromagnetic nearest-neighbour interactions resulting negative Curie-Weiss temperature, θCW = −12.62 K. Fe sublattice exhibits a weak ferromagnetic transition at TC ≈ 5 K. The frustration index f = |θCW|/TC becomes 2.5 indicative of moderate frustration, which may prevent Palmer-Chalker ground state configuration of Gd sublattice at lower temperature in the system. Heat capacity Cp exhibits a broad anomaly at ~3.1 K and calculated magnetic heat capacity Cm/T attains a peak at ~1 K, but is much weaker than for other pyrochlores Gd2B2O7 (B = Sn, Ti, Ge, Pt) which are all found to order at 1 K or lower, thereby reflecting a short-range second-order transition in Gd2FeSbO7. The nature of transition was also verified by Arrott plot of magnetization. Finally the magneto-thermodynamic data were analyzed on the basis of a cooperative two-sublattice model taking account of intra-sublattice (Gd−Gd and Fe−Fe) and inter-sublattice (Gd−Fe) magnetic interactions, defined by three molecular-field parameters, λGd−Gd = −0.71 T/μB, λFe−Fe = 0.87 T/μB, and λGd−Fe = −0.61 T/μB in presence of the easy-planer crystal-field anisotropy at Gd-site. Without Gd−Fe interaction, two independent interpenetrating Gd3+ and Fe3+Sb5+ sublattices can not precisely demonstrate the measured thermomagnetic properties of Gd2FeSbO7. This study thus revealed that 3d−4f magnetic interactions offer Gd2FeSbO7 a unique place in the series of gadolinium-based pyrochlores.

Absence of ferroelectricity in double-perovskite Y2CoMnO6 single crystals

The rare-earth double-perovskite R2CoMnO6 family has been reported to be promising multiferroics where the predicted ferroelectric polarization along the b-axis is induced by the Co2+/Mn4+ collinear magnetic order. In this work, we report our characterizations on the structural, magnetic, dielectric, and ferroelectric behaviors of flux-grown Y2CoMnO6 single crystals. A weak ferromagnetic transition with the Curie point TC ∼ 70 K is evident in combination with a remarkable magnetic hysteresis loop along the c-axis. The earlier reported dielectric anomaly at the magnetic transition is not detected in our single crystals. In addition, the peak of each electric current curve as a function of temperature, probed along different crystallographic directions, shows serious shifting with the temperature ramping rate, excluding the intrinsic ferroelectric contribution. The measured data are not in conformity with theoretical predictions and earlier experiments on polycrystalline samples. In addition, no reliable sign for magnetoelectric coupling can be detected. The present work seems to exclude the existence of magnetism-driven ferroelectricity in Y2CoMnO6.

Weak ferromagnetic insulator with huge coercivity in monoclinic double perovskite La2CuIrO6

Insulating ferromagnets with high TC are required for many new magnetic devices. More complexity arises when strongly correlated 3d ions coexist with strongly spin–orbit coupled 5d ones in a double perovskite. Here, we perform the structural, magnetic, and density functional theory (DFT) study of such double perovskite La2CuIrO6. A new P21/n polymorph is found according to the comprehensive analysis of x-ray, Raman scattering and phonon spectrum. The magnetization reveals a weak ferromagnetic (FM) transition at TC = 62 K and short range FM order in higher temperature range. A huge coercivity is found as high as HC ~ 11.96 kOe at 10 K, which, in combination with the negative trapped field, results in the magnetization reversal in the zero field cooling measurement. The first principle calculations confirm the observed FM state and suggest La2CuIrO6 of this polymorph is a Mott insulating ferromagnet assisted by the spin–orbit coupling.

Colossal dielectric, relaxor ferroelectric, diamagnetic and weak ferromagnetic properties of NdCrO3 perovskite nanoparticles

The NdCrO3 perovskite nanoparticles have been successfully synthesized using sol–gel auto-combustion process. Structural and morphological characterizations of the material have been performed at room temperature using XRD and SEM, respectively. Frequency- and temperature-dependent dielectric measurements have been performed in the range of 1 Hz–10 MHz and RT − 300 °C, respectively. The dielectric constant is found to be in the order of e′ > 103 at room temperature, indicating the colossal dielectric constant behaviour. Ferroelectric phase transition temperature has increased with an increase in frequency, suggesting that the material is a relaxor ferroelectric nature. Temperature- and field-dependent magnetization measurements have been carried out in the temperature range (5–400 K) and field up to 5 T. M–T curve exhibited a diamagnetic-like behaviour in low temperature and low fields. Two magnetic transitions were found at TN1 (223 K) and TN2 (33 K) which correspond to para to weak ferromagnetic transition and Nd3+ spin ordering, respectively. Hysteresis loop noticed weak ferromagnetism.