Fundamentals:
1. Heat energy is a function of the velocity of particles.
2. In non conductors heat energy is the velocity of vibrating atoms .
3. In metals (conductors) heat energy is the velocity of electrons in the atomic matrix .
4. The temperature of a metal is the average electron velocity (voltage) minus the voltage of the nucleus.
5. Absolute zero in metals is when electron velocity (voltage) equals the voltage of the nucleus.
6. Atoms with a magnetic moment are aligned by a magnetic field.
7. Electron free space is a function of atomic alignment.
8. The velocity of particles in an enclosed space is a function of volume.
9. When a magnetic material is placed in a field it's temperature increases.
10. When a magnetic material is removed from a field it's temperature decreases.
11. The velocity of electrons in a material subject to a changing field are polarized until random collisions distribute the increased velocity.
12. This is the property a magnetic motor needs to exploit.
13. The key is to find a material that will conduct a magnetic field without being magnetized by it.
I think such a material was used by a speaker manufacturer in the Twenties, Thirties or Forties to improve sound quality. See my post in Materials Wanted for details. 8)