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Understanding high-field amplitude electromagnetic heat loss phenomena is of great importance, in particular, in the biomedical field, because the heat-delivery treatment plans might rely on analytical models that are only valid at low field amplitudes. Here, we develop a nonlinear response model valid for single-domain nanoparticles of larger particle sizes and higher field amplitudes in comparison to the linear response theory. A nonlinear magnetization expression and a generalized heat loss power equation are obtained and compared with the exact solution of the stochastic Landau-Lifshitz-Gilbert equation assuming the giant-spin hypothesis. The model is valid within the hyperthermia therapeutic window and predicts a shift of optimum particle size and distinct heat loss field amplitude exponents, which is often obtained experimentally using a phenomenological allometric function. Experimental hyperthermia data with distinct ferrite-based nanoparticles and third harmonic magnetization data support the nonlinear model, which also has implications for magnetic particle imaging and magnetic thermometry. [ABSTRACT FROM AUTHOR]

We present anisotropic nonparabolic position-dependent effective-mass calculations of the bound energy levels of electrons confined in lens-shaped InxGa1-xAs quantum dots embedded in a GaAs matrix. The strain and In gradient inside the quantum dots and their wetting layer (due to the strong In segregation effect present in the InxGa1-xAs/GaAs system) were taken into account. The bound eigenstates and eigenenergies of electrons in a finite 3D confinement potential were determined by the full numerical diagonalization of the Hamiltonian. The quantum dots and their wetting layer were sliced into a finite number of monolayers parallel to the substrate surface, each one with a specific In concentration, in order to be able to reproduce any composition profile along the growth direction. A comparison between the eigenenergies of the 'pure' InAs quantum dots and the quantum dots with an inhomogeneous In content indicates that In segregation dramatically affects their electronic structure and must be taken into account if one wishes to accurately simulate the real optoelectronic properties of such nanostructures. [ABSTRACT FROM AUTHOR]