Both spin-torque oscillation spectra and dV/dI-I curves were measured for a metallic current-perpendicular-to-plane magnetoresistance (CPPGMR) device that had an elliptical nano-pillar shape. The spin-torque oscillation was emitted in a limited magnetic field range near the parallel state when a field was applied to the hard axis of the ellipse. The relative angle was estimated from the dV/dI-I curves for spin torque oscillation state. The relative angle change maintained an intermediate angle between parallel and anti-parallel states with a wide bias current range and the dV/dI-I curve hardly exhibited any hysteresis, peaks, or switching when the device emitted an rf signal. The oscillation frequency was stable against the bias current increase when the change in relative angle change was also stable.

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  In order to establish the basic technology of package level DC power grid for next generation power delivery to LSIs, Zn-ferrite core planar power inductor embedded in an organic interposer for power supply integrated in LSI package, has been fabricated and evaluated. Zn-ferrite core planar power inductor embedded in organic interposer had a footprint of 850×850 μm², 2-turn, 20 μm thick copper spiral coil sandwiched by top and bottom Zn-ferrite film magnetic core. For a comparison, a 3-turn air core spiral inductor was also embedded in the same organic interposer, which exhibited a large degradation of inductance at high frequencies because of eddy current induced by widespread high frequency magnetic flux passing through the lower layer Cu metal plane. Zn-ferrite core planar inductor had a relative small decrease of inductance at high frequencies. From 3D electromagnetic field analysis, it was found that the magnetic core inductor embedded in interposer has a great advantage of a possible three dimensional layout of the inductor with small influence on the near signal-line and circuit ground.

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  Ferromagnetic materials are widely used for various manufactured products such as cars, trains, and ships. Iron and steel are the most popular materials for frame structures because of their mechanical properties. Nondestructive testing of iron and steel is an extremely practical way of maintaining their mechanical reliability. It is well known that Barkhausen signals are only emitted from ferromagnetic materials having magnetic domain structures. These signals also vary depending on their past mechanical as well as radioactive stress histories.
  We applied a generalized analysis of frequency fluctuations to Barkhausen signals in the present study in order to detect various mechanical stresses. Surprisingly, we succeeded in clarifying that application of our frequency fluctuation analysis to the Barkhausen signals made it possible to detect several kinds of mechanical stresses.

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  This paper describes an ac / dc earth leakage current sensor using fluxgate magnetic sensor with self-excitation circuit for dc distribution system of photovoltaic power generation systems, data center systems, electric vehicles, and etc. The self-excitation circuit could be used in fluxgate current sensor to achieve a high sensitivity about ten times higher than conventional separate excitation circuit. The sensor achieves to detect a small ac / dc current of 10mA. Two kinds of detection by pulse width and pulse frequency could be used in this system to achieve a wide measurement range of 1:1000. Equivalent circuit analysis could be used in the fluxgate sensor to achieve optimized fluxgate current sensors characteristics of the sensitivity and a quiescent current. The sensor achieves a low quiescent current of 15mA and less. We found that the results from simulations almost corresponded to those from measurements, and were able to verify the validity of the basic analytical model. These concepts are realized by the simple configuration and low cost sensor, which a toroidal core based on thin-film nanocrystalline soft magnetic material, an excitation coil, and electric circuits.

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