We have investigated the crystal structure and the nature of the magnetic ground state of the polycrystalline compound Pr2FeCrO6 (PFCO) through X-ray diffraction (XRD), magnetization, and ...magnetocaloric effect studies. Analysis of the XRD pattern reveals that the PFCO compound exhibits a B-site disordered orthorhombic crystal structure. The random distribution of Fe3+ and Cr3+ magnetic sublattices at the B-sites of the crystallographic unit cell helps to generate several fascinating magnetic properties. The compound exhibits three distinct anomalies in both the temperature dependence of the magnetization and the magnetic entropy change (−ΔS) curves, namely, (i) a G-type canted antiferromagnetic (AFM) ordering of the transition metal ions (TN1), (ii) a progressive spin reorientation (SR) transition (TSR), and (iii) an AFM ordering of Pr3+ sublattices at very low temperature (TN2). Surprisingly, a novel “diamagnetism-like” behavior appears in the low-temperature region for low applied field values. Moreover, we have also constructed the thermal evolution of the magnetic crystal structures in different transition regions with the help of irreducible representations of the crystal symmetry. Overall, our study of B-site disordered PFCO may help to encourage basic fundamental and applied research on disordered rare-earth and transition metal-based perovskite systems due to their interesting magnetic properties over a broad temperature range.
Structural, magnetic, magnetotransport, and magnetocaloric effect of Heusler alloy Ni48.4Co1.9Mn34.2In13.8Ga1.7 have been studied. X-ray diffraction study at different temperatures and magnetothermal ...measurements performed at different applied magnetic fields reveal a transition from ferromagnetic state to a low magnetization state around 300 K, while the temperature is being decreased, is related to the austenite–martensitic structural transition. Near room temperature giant inverse magnetocaloric entropy change 18 J/kg-K and giant negative magnetoresistance (−66%) for 70 kOe magnetic field change have been observed around the first order magnetostructural transition.
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•Low temperature x-ray diffraction, martensitic transition.•Near room temperature giant inverse magnetocaloric effect.•Giant negative magnetoresistance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
In this work, we explore the influence of A-site ionic disorder (σ2) on magnetocaloric properties in relatively larger bandwidth manganite systems like, well known La0.7Sr0.3MnO3 compound. For the ...study, three isoelectronic manganites with same A-site ionic radius (〈rA〉=1.24Å) i.e. La0.7Sr0.3MnO3(σ2=1.85×10−3), Pr0.7Sr0.14Ba0.16MnO3(σ2=1.17×10−2) and Nd0.7Sr0.07Ba0.23MnO3(σ2=1.66×10−2) samples have been prepared. Magnetic measurements reveal that, upon increasing σ2 from 1.85×10−3 to 1.66×10−2, ferromagnetic double exchange interaction diminishes and as a result, ferromagnetic ordering temperature (TC) decreases from 360 K to 100 K. Accordingly, the magnetic entropy change (−ΔSM) has also been found to decrease from 4.6 J/kg-K to 4.1 J/kg-K on the application of 70 kOe magnetic field. However, for σ2=1.66×10−2, the value of −ΔSM=5.7J/kg is relatively larger compared to the other two values of −ΔSM. Additionally, increased σ2 (1.85×10−3 to 1.66×10−2) broadens the peak of −ΔSM which results in the increase in relative cooling power (RCP) from 80 J/kg to 121 J/kg on application of 20 kOe magnetic field. Critical analysis has been performed to explain the enhancement in RCP with σ2 and the anomaly in −ΔSM for Pr0.7Sr0.14Ba0.16MnO3(σ2=1.17×10−2) compound.
•Magnetic and magnetocaloric properties of isoelectronic manganites has been investigated.•Increase in Relative cooling power (RCP) is observed with increase of A-site ionic disorder for a fixed ionic radius.•The enhancement of RCP with A-site ionic disorder has been assessed by critical analysis.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The objective of the study was to develop an integrated drying system for optimal drying of button mushroom. Microwave (MW) was decided to be applied alternatively with convective hot air. Judicious ...application of microwave was decided by analysing the slope of the drying curves at every 10, 20 and 40 min of convective drying. The optimal time of MW application was found to be 20 ± 3 min based on minimum drying time and better quality attributes. The experiments were then performed on slice thickness of 2.5, 5 and 10 mm under optimal conditions (MW at 21st, 42nd, 63rd and 84th min of drying) and compared with conventional hot air drying in terms of drying kinetics, colour, water activity and rehydration ratio. The optimum thickness was found to be 2.5 mm which met the quality standards of commercial dried mushroom in relatively shorter time (72 min).
•Integrated drying system was developed for mushroom drying.•MW and hot air were applied alternatively for optimal drying of mushroom.•Time of application of MW was decided based on Inflection points calculated.•Quality of dried mushroom (72 min drying time) was at par with commercial product.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The magnetic properties of orthorhombic aluminides have recently been the subject of investigation, revealing several intriguing phenomena within this class of materials. However, the exploration of ...their magnetic and electrical transport phenomena has remained somewhat limited. In this study, we delve into the magnetic and electrical transport characteristics of one such material from that group which is DyFe2Al10(DFA). Our findings go beyond classifying this material as a simple antiferromagnet; but it posses a short range ferromagnetic ordering apart from helical spin structure of Dy3+. It exhibits a metamagnetic transition and spin glass behavior below its Néel temperature (TN). Our analysis of electrical magnetotransport behavior indicates the emergence of an antiferromagnetic superzone gap, resulting in a significant enhancement in magnetoresistance effect. This discovery paves the way for a class of materials with complex interactions and notable magnetoresistance properties.
•LSMO ultrathin films were deposited on Si/SiO2 by two-step growth method using PLD.•AFM revealed decreasing grain size and RMS roughness with lowering film thickness (t).•Metallic resistivity nature ...of LSMO films retained even in ultrathin range (~10 nm).•Resistance minima and low field MR enhanced with decreasing t, at low temperatures.•Low field MR enhanced due to intergranular Spin Polarized Tunnelling.
The magnetotransport properties of polycrystalline La0.7Sr0.3MnO3 (LSMO) ultrathin films depend strongly on their thickness and microstructure. In particular, the resistivity and magnetoresistance can be tuned by varying the film thickness and grain size. Here, we have deposited LSMO films with thicknesses ranging from 100 nm down to 10 nm by pulsed laser deposition on thermally oxidized Si substrates, retaining the films’ metallic nature. To avoid reaction of the films with SiO2 at high temperatures, we have introduced a two-step deposition method (half the film thickness grown at 400 °C and the remaining half at 800 °C). X-ray diffraction (XRD) revealed the polycrystalline nature, while atomic force microscopy (AFM) revealed the granular structure of the films from which, surface roughness and grain size are found to decrease with decreasing film thickness. However, low temperature resistivity upturn increases with decreasing film thickness and grain size. The variations of low temperature resistivity minima and magnetoresistance (MR) with film thickness and grain size have been interpreted in the regime of quantum interference effects (viz. weak localization and e-e interaction), intergranular spin polarized transport (SPT) phenomena and their dominance. It is found that SPT was the dominating phenomena. The signature of SPT was also evidenced clearly from low field MR at low temperatures. These kinds of ultrathin films are suitable as ferromagnetic electrode for spintronic device applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The magnetic and magnetocaloric properties of polycrystalline Gd0.5Sr0.5−xCaxMnO3 (x = 0.0, 0.2, 0.3, 0.4 and 0.5) compounds have been investigated. Depending upon the Ca and Sr proportions, ...fascinating magnetic ground states were observed in the Gd0.5Sr0.5−xCaxMnO3 compounds. Here, the dominating nature of the canted magnetic state (for the Gd0.5Ca0.5MnO3 compound) and glassy (disordered ferromagnetic) magnetic state (for the Gd0.5Sr0.5MnO3 compound) are observed. However, for the intermediate doped samples (x = 0.2, 0.3, 0.4), a competing nature is found in their magnetic and exchange bias properties. Additionally, in the low temperature region, a significantly large magnetocaloric effect is observed for all the samples. At a 70 kOe external magnetic field, the highest observed value of the magnetocaloric entropy change is 21.58 J kg−1 K−1 (for the Gd0.5Ca0.5MnO3 sample) and the lowest is 10.15 J kg−1 K−1 (for the Gd0.5Sr0.5MnO3 sample).
The modification of the magnetic ground state of the GdMnO3 compound has been explored with Y-doping on the Gd-site. The study on the magnetic properties indicates the existence of a weak ...ferromagnetic phase upon a 10% Y-doped sample. However, the strength of the ferromagnetic interaction becomes feeble in the 30% Y-doped sample. Such modifications of the magnetic ground states are analyzed considering the breaking of correlated weak ferromagnetic chains due to doping of non-magnetic Y-ions. In addition to that, the magnetocaloric effect has also been affected by the doping concentrations of Y-ions. The significant value of magnetic entropy change and relative cooling power of both the studied systems indicate the possible utilization of the materials as efficient magnetic refrigerants at the cryogenic temperature.
•Magnetic properties indicate the presence of weak ferromagnetic interactions in the compounds.•Magnetocaloric properties are highly influenced by the Y-doping concentrations.•The compounds exhibit large values of magnetic entropy change.•The compounds can be considered as promising refrigerant materials.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We present a comprehensive experimental study on the magnetic and magnetocaloric properties of a charge-ordered single-crystalline Sm0.5Ca0.25Sr0.25MnO3 compound. The studies on x-ray photoelectron ...spectroscopy (XPS) reveals the presence of an equal distribution of Mn3+ and Mn4+ ions in the studied system. The Oxygen, O1s-core level spectra have been simulated with three binding energies curves, which correspond to the O2− ions, O1− ions, and chemically adsorbed oxygens, Ochem. The XPS analysis of the O1s-core-level spectra and magnetic characterizations indicate the proper stoichiometry of the present sample. Considering the change of volume phase fraction in the isofield magnetization measurements during the first-order magnetic phase transition from paramagnetic state to ferromagnetic state, the isothermal magnetic entropy change (ΔS) has been estimated based on the modified Clausius–Clapeyron equation. An inverse magnetocaloric effect has also been noticed in the -ΔS vs. T plot calculated by Maxwell’s thermodynamic relation, suggesting the dominant antiferromagnetic ground state supported by a charge-ordered phase of the studied system. The high-temperature zero-field heat capacity (CP) data can be well-interpreted quantitatively using the Debye model of heat capacity. With the extracted magnetic heat capacity (Cmag) data, the temperature variation of the magnetic entropy (S(0)), as well as the adiabatic temperature change (ΔTad), have been estimated. In addition to that, the low-temperature CP data displays a Schottky-like anomaly in the temperature region between 2 K and 20 K. The experimental data points are successfully fitted by considering the various contributing factors of the low-temperature heat capacity such as the lattice-phonon vibration (Clat), antiferromagnetic spin-wave (Cmag), and the two-level Schottky function (Csch) due to the energy splitting of the Sm3+ cations.
•The impact of the charge-ordering phase on the magnetocaloric effect and zero-field heat capacity data have been noticed.•The XPS study reveals the presence of an equal distribution of Mn3+ and Mn4+ ions in the studied system.•The XPS analysis of oxygen core-level spectra and the magnetic characterization indicate the proper stoichiometry of the compound.•A strong signature of antiferromagnetic arrangements of magnetic sublattices has been noticed at the low-temperature region.•Due to the localization of charge carriers in the CO state, the value of specific heat increases at low temperatures.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Influence of the short range ordering on magnetocaloric effect have been discussed.•Reliability of Maxwell’s relation and Clausius-Clapeyron equation have been addressed.•Study highlighted the ...reliable method to calculate the magnetocaloric parameter.
Magnetic and magnetocaloric properties of polycrystalline Eu0.55Sr0.45MnO3 compound have been investigated. In addition to the field induced meta-magnetic transition, magnetically a mixed ground state (ferromagnetic and antiferromagnetic) was observed especially at the low temperature (T < 30 K). Influence of the predominant short range ferromagnetic interaction reflects in its magnetocaloric effect, calculated from Maxwell’s thermodynamic relation. However, different nature of the magnetocaloric effect, calculated using Clausius-Clapeyron equation, discussed considering the phase diagram of this material. Our study suggest, in contrast to the Maxwell’s relation, magnetocaloric parameter (-ΔS) derived from Clausius-Clapeyron equation gives the reliable value, useful for magnetic refrigeration cycle.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
