In navigation manuals, magnetic deviation refers specifically to compass error caused by magnetized iron within a ship or aircraft. This iron has a mixture of permanent magnetization and an induced (temporary) magnetization that is induced by the Earth’s magnetic field.

Your compass can also be temporarily thrown off course by using it too close to some metal objects (such as cars made of steel with an iron engine block) or electromagnetic fields generated by electricity cables. Bubbles! sealed capsule of fluid (often white spirit, paraffin or another mineral oil).

YBaCuO is a pretty good insulator (electrical current doesn’t flow through it easily); it is also an antiferromagnet (where adjacent spins point in opposite directions) up to around 450 K. If you add extra oxygen (up to 7.0) the extra holes can delocalize, making YBCO more metallic (albeit a rather “poor” metal).

All magnets can be demagnetized, and there are multiple ways to do that. Temporary magnets are items that are magnetic but do not keep their field as strongly. One of these methods requires increasing the temperature of the magnet. Another way to make a magnet lose its magnetic field is by hitting it.

heating or dropping a magnet on a hard surface weaken its magnetism BECAUSE a higher temperature or shock gives enough energy to the magnetic domains of the magnet to get disordered.

A permanent magnet always causes a force on other magnets, or on magnetic materials. Key features of a permanent magnet: it produces its own magnetic field. the magnetic field cannot be turned on and off – it is there all the time.

The easiest way to tell them apart is that a magnet can repel and attract another magnet. Whereas, a piece of magnetic material can only attract a magnet! Magnetic materials do not have fields around them, but they are affected by near by magnetic fields.