Magnetomechanical Resonance Research Articles

巨大ジャイロ磁気効果マイクロモータ

High-speed rotation of amorphous wire in an ac longitudinal field was investigated in relation to magnetostrictive vibration for Fe, Fe-Co, and Co based wires. It was found that high-magnetostriction Fe and Fe-Co based wires rotate around the wire axis, but low-magnetostriction Co based wire does not, and that the rotational speed is a linear function of magnetomechanical resonance freqency. It seems from these observations that the rotation of amorphous wire around its axis originates from the magnetostrictive vibration.

Development of a magnetoelastic resonant sensor using iron-rich, nonzero magnetostrictive amorphous alloys

A novel type of a magnetoelastic sensor which is based on the concept of the coupled magneto-mechanical resonance is described. Magnetic excitation of the tag results in some energy being stored in an elastic mode, much as in a tuning fork. When the magnetic excitation is turned off, the elastic energy sustains the magnetic oscillation through an exponentially decaying ring-down period that is a unique signature of the tag. This unique signal can be utilized principally as a sensor in electronic article surveillance. The goal of this investigation is to determine the relationships between processing parameters and the magnetic properties of the tag. The emphasis is placed on the operating principles of the sensor and special challenges in magnetic domain engineering and magnetic processing to optimize the sensor. The material requirement here is a magnetically soft material having nonzero magnetostriction.

Application of Smart Materials to Wireless ID Tags and Remote Sensors

ABSTRACTMaterial structures having an electromagnetic or magnetomechanical resonance can be excited or detected remotely using an antenna. Incorporating smart materials into such structures provides new opportunities to encode ID and sensor information in the electromagnetic signature of the “tag.” In this way, it is possible to create tags which not only have a unique ID but which can also respond to local changes in their environment (e. g. force, temperature, light, etc.). This principle forms the basis for a low-cost wireless ID and wireless sensor technology which has many potential applications in manufacturing, inventory control, security, surveillance, and new human-computer interfaces. As a means of illustrating this concept, two simple examples are given: a force sensor incorporating a piezoelectric polymer and a relative position sensor which incorporates a magnetoelastic amorphous metal ribbon.

Soft magnetic properties of ultrathin Fe-based amorphous alloy cores

Soft magnetic properties up to the megahertz range were investigated for Fe(Cr,Nb)SiB amorphous alloys of thickness 6–18 μm prepared by a single-roll method in vacuum. A low magnetic core loss of 1.5–2.0 W cm −3 at 1 MHz and 1 kG was attained by annealing near their crystallization temperatures. The annealing leads to the precipitation of excess α-Fe particles, so the d.c. coercive force changes drastically over 1 Oe. The magnetomechanical resonance effect due to magnetostriction in the initial permeability decreases upon substitution of Fe by Cr or upon annealing at higher temperature.