As the temperature increases, at a certain point called the Curie temperature, a magnet will lose its strength completely. Once the metal cools, its ability to attract magnets returns, though its permanent magnetism becomes weak. In general, heat is the factor that has the most effect on permanent magnets.

When a bar magnet is broken into two pieces then each piece will have unlike poles. Since magnetic monopole does not exist so if you do the breaking process repetitively then you will end up with each piece having unlike poles.

A permanent magnet can lose some or all of its magnetic field under certain circumstances. The Curie temperature of most samarium-cobalt magnets is on the order of 700-800°C (1300-1500°F). At these temperatures, the material itself will tend to break down magnetically.

It takes a big ac field to demagnetize those magnets at room temperature. You can demagnetize them by heating them to the Curie temperature, but that may be inconveniently high, e.g. 350°C. Another option is to heat to some lower temperature and apply a smaller ac field than would be needed at room temperature.

Exposing magnetized magnets to opposing external fields produces a demagnetizing effect. This effect is most apparent in permanent magnet materials having a non-linear demagnetization curve, such as Alnico. Other factors such as SHOCK and VIBRATION have very little effect on today’s permanent magnet materials.

It’s obviously not possible to turn off the magnetic field of a permanent magnet. But science empowers you to manipulate the situation. By playing around with various magnets and creating different interactions it is possible to alter the magnetic field.

The magnetic field generated by any magnet is always strongest at either pole. The magnetic force is equally as strong at both the north and south pole.