Should coercivity for making electromagnets be high?

Question

I have been studying the Hysteresis loop for ferromagnetic materials in my textbook. Now I know that coercivity represents the amount of current to apply in opposite direction of retained magnetic field so for any magnet, coercivity should be high so as to  prevent it losing out on its magnetic field due to external causes. Please answer in Yes/No format followed by an explanation. (It is not a homework problem)

user137289 · Accepted Answer

No, you want a low coercivity.
Typical application of an electromagnet is to hold a door open. You want the door to close when the current of the solenoid is switched off. So that means a low coercivity and a low remanence.
The same reasoning applies for other applications like a magnetic valve: you want the gas supply to stop when the electrical power disappears.
In other applications (doors of cupboards etc) one uses a permanent magnet.

hyportnex · Answer

It depends on what you wish to do with the magnetic material. If you want to use it as the core of an inductor then you wish to have $H_c$ as small as possible to reduce dissipation per AC cycle. If you want to have it as a permanent magnet then having as large $H_c$ as possible is a good idea because there is no need for changing the magnetic state and the larger the $H_c$ is the more difficult is to change it.

Answered by hyportnex on August 7, 2021

Should coercivity for making electromagnets be high?

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