In the pursuit of a clean and environmentally friendly future, magnetic refrigerator technology based on the magnetocaloric effect has been proposed as a replacement for conventional refrigeration technologies characterized by inefficient energy use, greenhouse gas emissions, and ozone depletion. This paper presents an in-depth exploration of the current state of research on magnetocaloric effect (MCE) materials by, examining various types of MCE materials and their respective potentials. The focus is particularly directed towards perovskite manganite materials because of their numerous advantages over other materials. These advantages include a wide working temperature range, easily adjustable Curie temperature around room temperature, excellent chemical stability, cost-effective production processes, negligible magnetic and thermal hysteresis properties, as well as competitive values for −ΔS_M and ΔT_ad compared to other materials. Additionally, crucial parameters defining the MCE properties of perovskite manganite materials are comprehensively discussed, both at a fundamental level and in detail.

In this review, the classification of magnetic materials exhibiting magnetoresistive properties is the focus of discussion because each material possesses different magnetic and electrical properties that influence the resulting magnetoresistance (MR) values. These properties depend on the structure and mechanism of the material. In this overview, the classification of magnetic materials with different structures is examined in several material groups, including the following: (1) perovskite structure (ABO₃), (2) alloy, (3) spinel structure, and (4) Kagome magnet. This review summarizes the results of each material's properties based on experimental findings, and serves as a reference for studying the characteristics of each material.

The development of Jakarta as a metropolitan city worsens the PM2.5 concentration in the area, causes health problems for the citizens, and becomes a major public concern. In this study, we use Pearson correlation and convergent cross mapping (CCM) to analyze any correlation between air quality and individual meteorological parameters, as well as the local PM2.5 nonlinear coupling pattern at two different locations in Jakarta. The influence of meteorological parameters and other pollutants in various seasons can be used to determine the variability of PM2.5. We found that the PM2.5 concentration is affected by PM10, SO2, and NO2 pollutant and is negatively correlated with precipitation, relative humidity, and the wind speed in all variations of the season. Causality analysis using CCM showed that PM2.5 coupling patterns differ for every season. The highest causality values (r) for air quality parameters are 0.74 (PM10), 0.68 (SO2), 0.52 (wind speed), and 0.51 (temperature). In Central Jakarta and South Jakarta, the coupling pattern of PM2.5 concentration and air quality parameters increased during the DJF (December-February) season, while the coupling pattern of PM2.5 concentration and meteorological parameters increased during the DJF and MAM (March-May) seasons. During the JJA (June-August) season, most of the meteorological parameters did not have any impact, whereas the increased humidity during the SON (September-November) season also increased the PM2.5 concentration. In conclusion, the significant outcome of our research is to show that individual air quality and meteorological parameters had an influence on local PM2.5 concentrations in the Jakarta region. In addition, it has been proved that CCM can analyze mirage correlation better than other correlation methods.

A pure-phase Cu ₂ O film photocatalyst was successfully prepared by the electrodeposition technique from a non-pH-adjusted solution. To investigate the phase evolution and photocatalytic activity of the film, the electrodeposition was conducted at different deposition temperatures. Photocatalytic activity of the films was evaluated from methylene blue (MB) dye degradation. The Cu ₂ O phase initially appeared at room temperature and its fraction was found to increase with increasing the deposition temperature, while the impurity phase was successfully diminished. A pure Cu ₂ O film with a narrow optical bandgap energy of 1.96 eV was obtained at 75°C. The multi-faceted crystals were found to form at 45°C and became a truncated octahedral structure that possessed {111} and {100} facets as deposition temperature further increased. A preferred orientation growth of {110} facet, which is known to possess a relatively high surface energy, was produced at 75°C. The performance of MB photodegradation enhanced gradually by increasing the deposition temperature. The increase of photocatalytic activity could be attributed to the rise of photoelectrochemical response and the decrease of resistance charge transfer because of narrowing bandgap energy, increasing Cu ₂ O fraction, and growing a relatively high catalytic activity facet which had escalated redox reaction that decomposed MB at the photocatalyst–solution interface.

This study investigates the effect of A-site disorder, (ionic radius (〈 r _A 〉) and the cation mismatch ( σ ² )) on the structural, magnetic, critical behavior, and magnetic entropy changes of in La _0.7 (Ba,Ca,Sr) _0.3 MnO ₃ manganites.

The on-site Coulomb potential, $U$, and the covalent state of electronic orbitals play key roles for the Cooper pair symmetry and exotic electromagnetic properties of high-$T_{\mathrm{c}}$ superconducting cuprates. In this paper, we demonstrate a way to determine the value of $U$ and present the whole picture of the covalent state of Cu spins in the mother system of the La-based high-$T_{\mathrm{c}}$ superconducting cuprate, ${\mathrm{La}}_2{\mathrm{CuO}}_4$, by combining the muon spin rotation $\left(\mu \mathrm{SR}\right)$ and the density functional theory (DFT) calculation. We reveal local deformations of the ${\mathrm{CuO}}_6$ octahedron followed by changes in Cu-spin distributions caused by the injected muon. Adjusting the DFT and $\mu \mathrm{SR}$ results, $U$ and the minimum charge-transfer energy between the upper Hubbard band and the O $2p$ band were optimized to be 4.87(4) and 1.24(1) eV, respectively.