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enter image description here#This is the diagram of hysterisis loop.

We know due to magnetisation of a ferromagnetic metal the curve reaches (a).Later due to demagnetization the curve reaches (b) and some energy is wasted as heat.

My doubt is where does this heat go.Is it released to surroundings or absorbed

by the metal.

My Second doubt is If it absorbed the heat then the further demagnetization occurs because heating should reduce the magnetic nature of metal.

Can you explain?

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  • $\begingroup$ published hysteresis curves usually assume isothermal measurements, that is at every point the temperature is maintained to be equal to that of the environment. The irreversible process inside the magnetic sample produces entropy that is shed to the environment so the sample's state (energy, entropy, magnetization, volume, etc.) returns to the same value during the cycle. $\endgroup$
    – hyportnex
    Apr 23, 2020 at 11:24
  • $\begingroup$ Is this a question about the mechanism for heating? There are answers for that in this forum, for example physics.stackexchange.com/questions/370299/… $\endgroup$
    – user137289
    Apr 24, 2020 at 9:02
  • $\begingroup$ There's also a reverse effect, magnetic refrigeration. $\endgroup$
    – PM 2Ring
    Apr 24, 2020 at 16:06

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Indeed, the magnetic system losses energy when going through the hysteresis curve. This are the hysteresis losses and heat up the magnetic element. The energy loss can be seen as an energy transfer from the magnetic system to the phononic system of the crystal (~heat). So, the magnetic energy loss is absorbed by the material itself. This, on its turn, heats up the material. Then, how this thermal energy inside the material is transferred to the surrounding (for example via conduction) is again another question that depends on the system.

What you mention in the second question is true. The absorbed heat will give more thermal energy to the material and this will indeed speed up the demagnetization process.

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