PURPOSE: To demonstrate the existence of magnetic domains and magnetic bubbles in a ferrimagnetic material.

DESCRIPTION: This device uses a commercial magnetic domain demonstrator, viewing it with a TV camera. The device uses polarized light to view the magnetization of domains in a ferrimagnetic garnet, which has the property of rotating the plane of polarization of the light by an angle dependent on its magnetization. Magnetic domain structure in the garnet is viewed as shown in the photograph. If the magnetic field in which the sample is positioned is increased the domain alignment becomes more complete, and the lines vanish, sometimes leaving a "magnetic bubble," a single small group of domains aligned opposite the surrounding area. Viewing is accommodated using a microscope objective lens on the end of a long tube attached to the TV camera, so that the image is created on the videcon of the camera. The analyzing polaroid, also contained in the tube, is rotated to the correct orientation for optimal viewing.


REFERENCES: (PIRA 5G20.20) See Demonstration Reference File for theory regarding ferrimagnetic garnet and details about the operation of this apparatus.

EQUIPMENT: Mounted magnetic domain demonstrator, TV microscope gizmo, light bulb, power supply with polarity switch, all mounted on TV monitor as in the photograph.

SETUP TIME: 10 min.

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