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Metasurfaces with bound states in the continuum (BICs) have proven to be a powerful platform for drastically enhancing light–matter interactions, improving biosensing, and precisely manipulating near- and far-fields. However, engineering metasurfaces to provide an on-demand spectral and angular position for a BIC remains a prime challenge. A conventional solution involves a fine adjustment of geometrical parameters, requiring multiple time-consuming calculations. In this work, to circumvent such tedious processes, we develop a physics-inspired, inverse design method on all-dielectric metasurfaces for an on-demand spectral and angular position of a BIC. Our suggested method predicts the core–shell particles that constitute the unit cell of the metasurface, while considering practical limitations on geometry and available materials. Our method is based on a smart combination of a semi-analytical solution, for predicting the required dipolar Mie coefficients of the meta-atom, and a machine learning algorithm, for finding a practical design of the meta-atom that provides these Mie coefficients. Although our approach is exemplified in designing a metasurface sustaining a BIC, it can, also, be applied to many more objective functions. With that, we pave the way toward a general framework for the inverse design of metasurfaces in specific and nanophotonic structures in general.

Presented is the second phase of a program conducted by Brothers of the Sacred Heart in their five schools in Louisiana and Mississippi, designed to gain insight into the opinions of students, parents, and teachers. This phase surveys parent opinions. Phases one and three survey teacher and student opinions, respectively. (KC)

Polycrystalline samples of (La1-xAx)0.67Ba0.33Mn1.05O3-δ, with A being a mixture of lanthanides containing 66% La, 22% Nd, 8% Pr, and 4% Ce, were prepared by the glycine-nitrate method, with target compositions of x=0, 0.33, 0.67, and 1. The effect of the mixture of lanthanides on the Curie temperature, TC, and the magnetocaloric properties was investigated. The prepared samples are single phase, with space group R3c. The lattice parameters and average A-site ionic radius, rA decrease linearly with x while the size disorder, as characterized by the variance, σ2, increases from 0.014 to 0.017 with x. As x is increased, the increase in σ2 drives a linear decrease in TC. The magnetic entropy change, ΔSM, for a field change of 1 T is obtained by magnetization measurements, giving a maximum value of 1.7 J/kg K, and a relative cooling power of 43 J/kg, independent of x. These results suggest that replacing lanthanum with a mixture of lanthanides is a realistic way to tune the working temperature of magnetocaloric manganites while maintaining a constant magnetocaloric effect. [ABSTRACT FROM AUTHOR]

Magnetization curves recorded at high sweep-rates on magnetic materials near a phase transition temperature can be affected by temperature changes in the material due to the magnetocaloric effect. This change in the sample temperature is a result of the quasiadiabatic conditions that can occur under such conditions and we demonstrate its effects on magnetization curves of two magnetocaloric materials, La(Fe0.945Co0.055)11.9Si1.1 and Gd5Si2Ge2. We show how a quantity calculated from isothermal magnetization curves, the magnetic entropy change, ΔSM, is affected by the erroneous data. As ΔSM is a measure of the magnetocaloric effect, the discrepancies demonstrated here are more severe close to a peak in ΔSM, which is precisely the quantity that is of interest and reported on in the literature from possibly erroneous magnetization data. We also demonstrate how, through simple measurements and without a direct measurement of the sample temperature, one can determine an appropriate sweep-rate of the magnetic field. [ABSTRACT FROM AUTHOR]

We present x-ray absorption and x-ray magnetic circular dichroism studies of iron oxide passivated iron nanoparticles. The combination of measurements with different probing depths allows us to determine the oxide composition while the magnetic data reveal the magnetic interactions across the interface between the α-Fe core and the spin canted ferrimagnetic iron oxide shell. These studies shed light on the mechanisms that govern the magnetic properties of core-shell nanoparticles. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Polycrystalline samples of [([La.sub.1-x][A.sub.x]).sub.0.67][Ba.sub.0.33][mn.sub.1.05][O.sub.3-[delta]] (with A being a mixture of lanthanides containing 66%La, 22%Nd, 8%Pr and 4%Ce) are prepared by the glycine-nitrate method. The results have shown that replacing lanthanum with a mixture of lanthanides is a good way to tune the working temperature of magnetocaloric manganites while maintaining a constant magnetocaloric effect.