In magnetic random access memory (MRAM), power consumption depends on the coercivity of the magnetic elements in the memory cells. In this paper a new method is described that uses a “domain wall trap” element shape to reduce both the coercivity and the dependence of coercivity on element size in submicron magnetic elements. Micromagnetic simulations of a shaped Permalloy element show coercivit...

We report experimental evidence that submicron-scale local coercivity variation determines magnetization reversal dynamics in ferromagnetic thin films. Local coercivity distribution is generated from a twodimensional array of hysteresis loops each of 0.3230.32 mm spots simultaneously measured using a magneto-optical microscope magnetometer. We directly demonstrate that domain reversal pattern i...

A reduction process of the substituted Ba-ferrite has been found to be devided into three steps. At the first and second steps, the magneto-plumbite structure maintains and the coercivity increases. When the reduced-substituted Ba-ferrite particles are reoxidized, the coercivity is reversible in the first step but irreversible in the second step. During the third step, the magneto-plumbite stru...

Single-crystal thin films of the antiferromagnet FeF2 have been used to exchange bias overlayers of Fe. An unexpected coercivity enhancement is observed at temperatures above the Néel temperature of the FeF2. This coercivity reaches a peak value of over 600 Oe close to the Néel temperature and persists to above 300 K. The coercivity is correlated with the growth of an anisotropy in the ferromag...

Hard/soft permanent magnets have aroused many interests in the past two decades because of their potential in achieving giant energy products as well as their rich variety of magnetic behaviors. Nevertheless, the experimental energy products are much smaller than the theoretical ones due to the much smaller coercivity measured in the experiments. In this paper, the deterioration of the coercivi...

We report the temperature and cooling field dependence of the coercivity of exchange biased MnF(2)/Fe bilayers. When the antiferromagnetic surface is in a state of maximum magnetic frustration and the net exchange bias is zero, we observe a strong enhancement of the coercivity, which is proportional to the exchange coupling between the layers. Hence, the coercivity can be tuned in a reproducibl...

In this article we introduce a stability concept for the coercivity of multivariate polynomials f ∈ R[x]. In particular, we consider perturbations of f by polynomials up to the so-called degree of stable coercivity, and we analyze this stability concept in terms of the corresponding Newton polytopes at infinity. For coercive polynomials f ∈ R[x] we also introduce the order of coercivity as a me...

It is well known that the coercivity of magnetic nanomaterials increases up to a maximum and then decreases to zero with decreasing particle size. However, until now, no single synthesis method has been able to produce magnetic nanoparticles with a wide range of sizes, i.e., from 10 to 500 nm, in order to uncover the coercivity evolution. Here we report the characterization of magnetite (Fe3O4)...

Understanding the coercivity mechanism has a substantial impact on developing novel permanent materials. However, the current coercivity mechanisms used widely in permanent alloys cannot explain well the amorphous phase produced hard magnetic behavior of Nd-based bulk amorphous alloys (BAAs). Here, we propose that the coercivity in as-cast Nd60Fe30Al10 alloy is from the combination of magnetic ...