To develop a full understanding of interactions in nanomagnet arrays is a persistent challenge, critically impacting their technological acceptance. This paper reports the experimental, numerical and analytical investigation of interactions in arrays of Co nanoellipses using the first-order reversal curve (FORC) technique. A mean-field analysis has revealed the physical mechanisms giving rise t...

The temperature dependence of the magnetic viscosity coefficient (Sv), the activation volume (Vact) and the coercivity (Hc) were examined for CoCrTa/Cr and CoCrPtTa/Cr thin films in the temperature range from 200 to 423 K. This experiment shows that the medium noise measured for 150 kFCI is approximately proportional to kT/Sv (=Vact X Ms) at 298K. kT/Sv and the temperature variation of coercivi...

The abstract nonlocal boundary value problem −d2u t /dt2 Au t g t , 0 < t < 1, du t /dt − Au t f t , 1 < t < 0, u 1 u −1 μ for differential equations in a Hilbert space H with the self-adjoint positive definite operator A is considered. The well-posedness of this problem in Hölder spaces with a weight is established. The coercivity inequalities for the solution of boundary value problems for el...

The ultrathin SmCo5 nanoflakes with average thickness smaller than 50 nm are prepared by a novel method of solid particle (NaCl) and surfactant co-assisted ball milling. The as-prepared nanoflakes exhibit a narrower thickness distribution of 10-50 nm and high coercivity of 23 kOe. The possible formation mechanism of nanoflakes are proposed. Temperature dependence of demagnetization curves indic...

The coercivity mechanism of Nd-Fe-B thin film samples with and without Nd deposition was investigated by simultaneous chemical and magnetic imaging by means of X-ray magnetic circular dichroism-photoemission electron microscopy. The two Nd-Fe-B thin film samples exhibited almost the same surface morphology and magnetic domain patterns, but their coercive fields were quite different, being 0.98 ...

This paper is the third and last part of a work attempting to give a unified analysis of Discontinuous Galerkin methods. The purpose of this paper is to extend the framework that has been developed in part II for two-field Friedrichs’ systems associated with second-order PDE’s. We now consider two-field Friedrichs’ systems with partial L2-coercivity and three-field Friedrichs’ systems with an e...

Single-phase Zr2Co11 nanomagnetic materials with high coercivity have been fabricated by melt spinning with subsequent annealing under Ar, N2, and vacuum. Annealing coarsens the grains and decreases the density of defects, leading to intergrain decoupling action and the enhancement of the magnetocrystalline anisotropy field of the hard magnetic phase. Therefore, coercivity increases 44.7% from ...

Co dot and antidot arrays with hexagonal symmetry have been prepared by combined electrochemical and sputtering techniques with significantly reduced nanoscale dimensions. Their magnetization reversal process has been analyzed on a macroscopic scale with Vibrating Sample Magnetometry (VSM) and on a microscopic scale by high spatial resolution Magnetic Transmission Soft X-ray Microscopy (MTXM). ...

We consider a finite element approximation of elliptic partial differential equations with random coefficients. Such equations arise, for example, in uncertainty quantification in subsurface flow modelling. Models for random coefficients frequently used in these applications, such as log-normal random fields with exponential covariance, have only very limited spatial regularity, and lead to var...

This work reports on the magnetic reversal of sub-μm sized elements consisting of an CoFeB/Ru/CoFeB artificial ferrimagnet (AFi). The elements were patterned into ellipses having a width of approximately 250 to 270nm and a varying aspect ratio between 1.3 and 8. The coercivity was found to decrease with an increasing imbalance of the magnetic moment of the two antiferromagnetically coupled laye...