Magnetization current when two magnets are brought together and the Lorentz force law

Question

Suppose we have two ferromagnetic objects constituting two permanent magnets. A classical way to think of the two magnets repelling/attracting each other would be by ascribing bulk and surface currents on the magnets and using the Lorentz force law.

When we have two horizontal loops of wire, with one loop above the other, and both having current going in the same direction, the two loops end up attracting one another. When one loop is moving towards another, the Lorentz force law redirects the motion of charges from an azimuthal motion around the loop to the motion in direction of the loop's velocity. This means the current around the loop has to decrease unless we increase the output of a battery that drives the current.

In the case of two magnets being attracted, when one magnet is moving towards the other, the same thing to the magnetization current should happen (in which the Lorentz force law should redirect the current into the motion of the magnet). However, if the magnetization of the moving permanent magnet stays the same, then the current should stay constant. So then my question is, in analogy to the "two loops scenario," what would be the analogue of the battery that keeps the current constant? Or is there any assumption I am making here that invalidates the question?

Answer 1

(I would have commented this if I had enough reputation, but here goes)
In the first scenario, where two current carrying loops are mentioned, you are absolutely right.

But in the second scenario, the place where there is a mention of "constant magnetization", is a bit odd.
Consider these statements.

1. In classical electromagnetism, magnetization is the vector field that expresses the density of permanent or induced magnetic dipole moments in a magnetic material. Accordingly, physicists and engineers usually define magnetization as the quantity of magnetic moment per unit volume.
2. In electromagnetism, the magnetic moment or magnetic dipole moment is the combination of strength and orientation of a magnet or other object or system that exerts a magnetic field.

The above statements are the definitions of magnetization and magnetic dipole moment as per Wikipedia.

Therefore, it is somewhat intuitive that influencing the magnetic field of an isolated system will, in fact change these two factors defined above.

In most of the practical conditions though, this change is observed to be minimal(Just like the reverse electromotive force generated in the loop is somewhat negligible with respect to the battery to which the loop has been connected).

I have hopefully answered your question.

Resources
a)https://en.wikipedia.org/wiki/Magnetization#:~:text=In%20classical%20electromagnetism%2C%20magnetization%20is,magnetic%20moment%20per%20unit%20volume.
b) https://en.wikipedia.org/wiki/Magnetic_moment

Answer 2

When the current loops approach each other, they experience a back EMF that acts to decrease the current flowing in each loop. (The source of this back EMF depends on the frame of reference. A purely stationary current loop experiences an EMF due to the induced magnetic field under the Maxwell–Faraday law, while a current loop that is moving while its partner stays still experiences only the Lorentz force. If both loops are moving, then both effects will occur to both loops.)

But the extent to which the current in each loop actually decreases depends on the resistance and inductance of each loop, which are not given. So you can't calculate the change in current without having more details.

When dealing with permanent magnets under conditions that don't appreciably affect their magnetization, we're effectively making a simplifying assumption that the permanent magnets are made up of current loops with infinite self-inductance, i.e., an ability to perfectly cancel out any change in current. As a result, the back EMF has no effect on their magnetic moments.

(Of course, this model of current loops with infinite inductance isn't physically realistic, which is a sign that the source of permanent magnetism has a quantum-mechanical explanation.)