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.
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.
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.
•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.
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.
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.
•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.
•Magnetic, magnetocaloric and magnetotransport properties of x=0, 0.2 compounds have been studied in detail.•Chemical pressure changes the ferromagnetic insulator ground state to the ferromagnetic ...metallic one.•Increase in RCP has been observed in the La-doped compound.•An enhancement of magnetoresistance at room temperature is also observed in the compound.
The effect of chemical pressure on the ferromagnetic insulator ground state and its effect on magnetotransport and magnetocaloric properties has been explored in this study. Magnetic and magnetotransport measurements reveal that the increased chemical pressure in Pr0.6La0.2Sr0.2MnO3 due to the partial substitution by La in Pr0.8Sr0.2MnO3 compound change the low-temperature insulator phase to the metallic phase. A room temperature enhancement of magnetoresistance (MR), as well as large relative cooling power (RCP), have been achieved with increasing chemical pressure in x = 0.2 compound. This enhancement of MR and magnetocaloric effect (MCE) in Pr0.6La0.2Sr0.2MnO3 compound have been attributed to the short- range ferromagnetic cluster formation at higher temperature (T>TC).
•The magnetocaloric effect is employed as a powerful tool to study the modification of the magnetic ground state of the compounds.•Distinct nature in the magnetocaloric effect is addressed by ...considering the field-induced modification of short-range ordering in the low-temperature regime.•Significantly large magnetocaloric effect along with large magnetic cooling capacity has been observed which may be beneficial from the application aspects.
Detail investigation on the influence of Gd-doping both in the magnetic and magnetocaloric properties of (Sm1-yGdy)0.55Sr0.45MnO3 (y = 0.5 and 0.7) compounds has been carried out. With the Gd-content, the studied compounds exhibit quite distinct physical properties in the presence of an external magnetic field. In addition to the field-induced meta-magnetic transition and quantitatively large magnetocaloric effect, both the compounds reveal significant relative cooling power and refrigerant capacity. However, in the low temperature region, different nature in magnetocaloric effect was addressed by considering the field induced modification of short-range ordering.
•Synthesis of bulk and nanocrystalline La0.4(Ca0.5Sr0.5)0.6MnO3 compounds.•Enhancement of ferromagnetic clusters in core part with size reduction is noticed.•Magnetic inhomogeneity induced glassy ...magnetic phase is observed in nanomaterial.•Magnetic disorder results in strong memory and exchange bias effect in nanocrystal.•Theoretical model for core-shell structure corroborates the short-range correlation.
A comparative study of low temperature magnetic properties for bulk and nanocrystalline La0.4(Ca0.5Sr0.5)0.6MnO3 compounds has been presented here. Considerable enhancement of exchange bias as well as magnetic memory effect in nanocrystalline material has been observed compared to bulk. Substantial increase of ‘A’ -site size-disorder parameter (σ2) with ‘Sr’ doping concentration in La0.4Ca0.6MnO3 compound is found to assist in destabilizing the charge ordering state along with a grow of ferromagnetic clusters in these systems. In nanomaterial, the short-range magnetic interaction between the increased ferromagnetic cluster and the antiferromagnetic matrix in the core part of the core-shell structure assists to develop strong magnetic disorder (glassy phase) in the system. Additionally, the magnetic interaction of uncompensated shell spins and its interaction with adjacent core ferromagnetic clusters also attribute to grow glassy phase in the system, resulting in strong memory effect and exchange bias effect. The experimental findings have been described in terms of different theoretical models developed for core-shell structure.
