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In this work, we studied in detail the magnetic and magnetocaloric properties of the La0.7Ca0.2Ba0.1MnO3 compound according to the phenomenological model. Based on this model, the magnetocaloric parameters such as the maximum of the magnetic entropy change ΔS M and the relative cooling power (RCP) have been determined from the magnetization data as a function of temperature at several magnetic fields. The theoretical predictions are found to closely agree with the experimental measurements, which make our sample a suitable candidate for refrigeration near room temperature. In addition, field dependences of ${{\Delta } S}_{\mathrm {M}}^{\max }$ and RCP can be expressed by the power laws ${\Delta S}_{\mathrm {M}}^{\max }\approx a$ (μ 0 H) n and RCP ≈b(μ 0 H) m , where a and b are coefficients and n and m are the field exponents, respectively. Moreover, phenomenological universal curves of entropy change confirm the second-order phase transition.

A molecular dynamics simulation has been conducted in Ni73Co27 and Ni74Co26 alloys during rapid solidification at the cooling rate of 1 × 1012 K/s. It indicates that two phase transitions occur with twice drops, and the number of FCC increases suddenly in Ni73Co27 alloy. And finally, FCC atoms are dominant with the amount of 92.94% at 300 K, which neatly arranges themselves into the crystalline structure. A lot of topologically close-packed clusters are formed in Ni74Co26 alloy, indicating the formation of metallic glass. The differences between the formations in crystalline hexagon and amorphous pentagon are demonstrated by three-dimensional visualization.

Asymmetric quantum well potentials are expected to produce a conduction band spin-splitting which contributes to Dyakonov–Perel (Sov. Phys. Solid State 13:3023, 1971) spin relaxation. Much experimental work has focused on the effect of an electric field on spin dynamics (Karimov et al., in Phys. Rev. Lett. 91:246601, 2003) and little on asymmetry from alloy engineering. By combining time-resolved Kerr rotation measurements with transient spin grating measurements in GaAs/AlGaAs quantum wells we have compared the conduction band spin-splitting resulting from asymmetric alloy engineering with that from applied electric field. The latter is easily measurable, whilst the former is no greater than that in symmetric wells. These results are consistent with an envelope function approximation model that considers the potential profile in both the conduction and the valence bands (Winkler, in Springer Tracts in Modern Physics, vol. 191, 2003).

Magnetic nanoparticles of La0.67Sr0.33MnO3 (LSMO) with mean particle sizes of 13, 16, 18, and 21 nm were prepared by the sol–gel method. The samples were characterized by X-ray diffraction (XRD) using Rietveld refinement and transmission electron microscope (TEM). Fourier transform infrared (FTIR) transmission spectroscopy revealed that stretching and bending modes are influenced by annealing temperature. Dc magnetization versus magnetic field of the samples was carried out at room temperature. Magnetic dynamics of the samples was studied by the measurement of ac magnetic susceptibility versus temperature at different frequencies and ac magnetic fields. A frequency-dependent peak was observed in ac magnetic susceptibility versus temperature which is well described by Vogel–Fulcher and critical slowing down laws, and empirical $c_{1} = \frac{\Delta T_{f}}{T_{f}\Delta (\log _{10}f)}$ and $c_{2} = \frac{T_{f} -T_{0}}{T_{f}}$ parameters. By fitting the experimental data with Vogel–Fulcher magnetic anisotropy energy and an effective magnetic anisotropy constant have been estimated. The obtained values support the presence of strong interaction between magnetic nanoparticles of LSMO.

Zn0.99M0.01O (M = Ni, Fe, and Cd) nanoparticles have been prepared by a co-precipitation technique. X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), and Fourier transformation infrared spectroscopy (FTIR) have been used to characterize the prepared samples. XRD patterns showed that ZnO has a hexagonal wurtzite structure with an average particle size of 22.9 nm, which decreased by the addition of metals ions to ZnO. EDS exhibited the existence of Cd, Ni, and Fe which asserts the substitution of metal ions inside ZnO matrix. The UV-Visible spectra revealed an absorbance increase and a band gap decrease by metals ions addition. Dielectric permittivity (ε`), electric modulus (M``), and ac conductivity (σac) were also studied as a function of temperature and frequency. ε` was found to increases with metal ions addition, and a relaxation peak appears at low frequency in M`` spectra. σac(T) was thermally activated and the activation energy Ea decreased with metal ions addition. A ferromagnetic behavior with a hysteresis loops was observed for Zn0.99M0.01O at room temperature. These results suggest that Zn0.99M0.01O is suitable for optoelectronic device applications or as a novel way for the incorporation of magnetic ions in the semiconductor materials.