For Co and CoNi single layer films, the coercivity is a linear function of the inverse layer thickness and has an angular dependence of a fourfold-like symmetry although only a uniaxial anisotropy exists. For both as-prepared and post field-cooled Co/FeMn bilayers, the exchange field and the coercivity enhancement are proportional to the inverse Co thickness. For as-prepared ones, the exchange ...

The local coercivity distribution of CoCrPt alloy films prepared by dc magnetron sputtering has been investigated by means of magneto-optical microscope magnetometer, capable of simultaneously measuring the local magnetic properties on a submicrometer spatial resolution. We find that with increasing Pt concentration the local coercivity distribution becomes asymmetric and the average local coer...

The high coercivity of 26.2 kOe for SmCo5 nanoflakes are obtained by multistep (three steps) surfactant-assisted ball milling. The magnetic properties, phase structure and morphology are studied by VSM, XRD and SEM, respectively. The results demonstrate that the three step ball-milling can keep more complete crystallinity (relatively less defects) during the process of milling compared with one...

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...

We have carried out extensive measurements on novel Fe₃O₄-γ-Fe₂O₃ core-shell nanoparticles of nearly similar core diameter (8 nm) and of various shell thicknesses of 1 nm (sample S1), 3 nm (sample S2), and 5 nm (sample S3). The structure and morphology of the samples were studied using X-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electron diffraction (SAED)...

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...

The underlying mechanism of coercivity in permanent magnets has been a topic of intense interest for many years. It is motivated by the fact that the measured coercivity approaches only 20%–40% of the theoretical nucleation fields as derived from micromagnetic theory. We address this problem by proposing an analytical model, within the framework of the micromagnetic approximation, to examine th...

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...