Bertotti’s excess eddy-current model combined with the Cauer circuit can be used to represent the properties of eddy-current loss in a silicon steel sheet. Measurement results revealed that the excess eddy-current field coefficient in Bertotti’s model depends on the magnetic flux density. We introduce a flux-density-dependent coefficient in Bertotti’s model. We derive an integral equation for the coefficient, relating it to the measured excess eddy-current loss. Thereafter, we solve it analytically to identify the flux dependence, without parameter fitting to assumed functions for some specific materials. The iron loss evaluation of the silicon steel sheet is improved by incorporating the flux-dependent coefficient into the Cauer circuit.

  Magnetic powder core materials for inductors used in power electronics require high saturation magnetization, low coercivity, and low eddy current losses. Since forming an insulating shell on a particle is effective for suppressing intra–grain eddy currents, in this study investigation of the formation of oxide shells on Fe–Si particles via gas–solid reactions with a particular focus on particle size is performed. For the micronpowder, oxygen diffuses into the particle interior over 100 nm from the surface and hematite phase is formed under 500 °C. Thus, internal oxidation is found to be progressed. The micronpowder after oxidation exhibits high electrical resistivity maintaining soft magnetic properties, compared to that before oxidation. For the nanopowder, the oxygen and silicon, and the pure iron are localized in the 5 nm–thick shell and in the tens nanometer–sized core at an extremely low temperature of 120 °C. Thus, surface oxidation is found to be occurred. The nanopowder after oxidation shows relatively high electrical resistivity with a minimal drop in saturation magnetization, compared to the powder before oxidation. These results indicate that the oxidation mechanisms differ between micron– and nanometer–sized Fe–Si magnetic particles.

  This study systematically investigates Ohmic leakage in micrometersized devices for chirality-induced spin selectivity (CISS) measurements using a 3D resistor network model. While the influence of Ohmic leakage is consistent with the behavior obtained by the conventional 2D model at low resistivities, saturation appears above 10 μΩcm, which is attributed to the resistance mismatch between the sample and the electrodes. The nonlocal signals experimentally observed for CrNb₃S₆ and NbSi₂ are found to exceed simulated values due to Ohmic leakage, providing evidence that signals are intrinsic to the CISS.

  The magnetic losses generated when an alternating magnetic field is applied to magnetic nanoparticles can be used as the heat required for cancer hyperthermia therapy. Furthermore, magnetic nanoparticles can be used in medical imaging for detecting the resulting changes in magnetization from outside the body. Many challenges must be overcome before these diagnostic and therapeutic methods can be used with humans, that is, in clinical practice. This article provides a detailed review of the magnetic properties of commercially available magnetic nanoparticles. We discuss measurement results for multicore particles, particle clusters with specific diameters, and the respective samples in which the easy axes of magnetization are aligned. This review provides fundamental insights into the key challenges in improving the heat generation of magnetic nanoparticles and the detection sensitivity in imaging.