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Unformatted text preview: 1 PHYS809 Class 26 Notes Induced and permanent magnetization terminology Due to the motion of their electrons, some atoms and molecules can have intrinsic magnetic moments. Other atoms develop magnetic moments when placed in an external magnetic field. If the atoms or molecules have zero magnetic moment, then an applied magnetic field induces magnetic moments that are aligned anti-parallel to the applied field. The material is said to be diamagnetic (an example is CO 2 ). If the atoms or molecules have non-zero magnetic moments that point in random directions then the sum over many atoms gives zero magnetization. An applied field tends to align the magnetic moments parallel to the applied field. The material is said to be paramagnetic (an example is liquid O 2 ). If atoms have non-zero magnetic moments that point in the same direction then the sum over many atoms gives finite magnetization. The material is said to be ferromagnetic (examples are Fe, Ni, Co). A number of other terms are used to describe magnetic properties of materials. For example, magnetite is ferrimagnetic . In ferrimagnets, magnetic dipoles are anti-parallel in arrangement but in such a way that there is a net magnetization....
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- Fall '11
- Magnetic Field, µ, current density, magnetic moments