The present paper is dedicated to the numerical solution of stationary free boundary problem by means of shape optimization. We assume that the state satisfies the Dirichlet problem and track the Neumann data at the free boundary. The gradient and Hessian of the shape functional under consideration are computed. By analysing the shape Hessian in case of matching data a sufficient criterion for ...

The temperature dependence of the coercivity of Sm–Co based magnets is investigated by magnetization measurements and model calculations. The Zr-free titanium-substituted Sm–Co material exhibits a positive temperature coefficient of the coercivity (TCC) above room temperature, a reasonable hysteresis-loop shape, and an appreciable coercivity of 12.3 kOe at 500 C for the nominal composition Sm(C...

Many interesting properties of polynomials are closely related to the geometry of their Newton polytopes. In this article we analyze the coercivity on Rn of multivariate polynomials f ∈ R[x] in terms of their Newton polytopes. In fact, we introduce the broad class of so-called gem regular polynomials and characterize their coercivity via conditions imposed on the vertex set of their Newton poly...

We report our experimental finding that magnetic properties of Co-based multilayer films are shown to exhibit their local variations far from the Gaussian ~or Lorentzian! distribution which are usually assumed. The local variations of the coercivity and the field dependence l(52]ln t/]H) were determined from measurements of the hysteresis loop and the field-dependent switching time t , respecti...

The coercive field and angular dependence of the coercive field of single-grain Nd2Fe14B permanent magnets are computed using finite element micromagnetics. It is shown that the thickness of surface defects plays a critical role in determining the reversal process. For small defect thicknesses reversal is heavily driven by nucleation, whereas with increasing defect thickness domain wall de-pinn...

oxide nanoparticles of fe-co-ni were prepared in six different compositions by co-precipitation method. the as-synthesized nanoparticles were characterized by x-ray diffraction (xrd), field emission scanning electron microscope (fesem), fourier transform infrared (ft-ir) and vibrating sample magnetometer  (vsm). it was found that the nanoparticles had mean crystalline size of 30-55 nm and spher...

Lorentz microscopy combined with conventional transmission electron microscopy were used to image the magnetic domains and microstructures of sintered Sm~CobalCuxFe0.06Zr0.03)z ~0.088<x <0.128; 5.8<z<7.2! permanent magnets which were specifically designed for high temperature applications. The microstructural data were correlated with the magnetic measurements to understand the origin of coerci...