A new measurement system for magnetic anisotropy with pulsed rotation field

A novel approach for the measurement of magnetic anisotropy is introduced, and a preliminary small-scale system is described. In order to create a rotating magnetic field without mechanical rotation of the electromagnet, two pairs of electromagnets are placed so that their axes are mutually perpendicular. One of the pairs of electromagnets is excited with a sinusoidal current and the other with a cosine current. Thus, the net magnetic field vector rotates. The exciting currents are intermitted by a zero crossing analog switch to minimize power loss in the electromagnets and power supplies. The rotating magnetic field generates a torque on the magnetically anisotropic sample placed in the center of the field. The torque is measured with a piezoelectric sensor. In a preliminary experiment, a rotating field intensity of 0.2 T was obtained with a 1-kg electromagnet and a 20-W power amplifier. The calibration for the measurement was carried out with pure nickel wire. The anisotropy constants of several amorphous ribbons were measured.<
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