Does magnetic attraction power of magnet decay over time? I probably have a common question to start with. Does the magnetic attraction power of a permanent magnet for example, decay over time, if the magnet is actively used to attract stuffs and perform some work? Then I have couple of followup questions based on the answer of the above question.

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*If Yes, it decays - let's say a moderate sized neodymium magnet can hold/suspend an iron bar weighing approx 10 kgs for atleast 1 year. Isn't that a huge amount of energy which is required for this suspension work? Is the magnetic power of the magnet decaying as fast as it takes to keep a 10 kg iron bar suspended, per year? Is it possible unless  mass to energy conversion happens? What at the atomic level of neodymium is supplying this huge amount of energy?


*If No, it doesn't decay - how conservation of energy withstands when a magnet is used to hold/suspend an iron bar say for 1 year?
I doubt, I might have some misconceptions on this topic, please help me understand.
 A: "Permanent" magnets are not completely permanent. Magnets get their magnetism by the alignment of the many current loops comprising the magnet. Over time, effects such as heat, impacts, and other magnetic fields can decrease the strength of the magnet by randomizing the orientation of each of these loops. They can also loose their strength just by sitting there for long periods of time$^1$.
So the magnetic strength of a magnet does decrease over time.
Also, the example you have given does not require for the magnet to move itself or move another object, and so no work is being done, meaning the system is not losing energy.
There is indeed a magnetic force that's required to hold up the iron bar,  but since it does not move the bar, no energy needs to be expended. Remember that the work done by a force is given by $$W=\int {\bf F}\cdot {\bf dS}$$ and since the displacement ${\bf dS}=0$ then so too is $W=0$.
The same could be said about bookshelves holding up books. No energy is being expended in such cases too.
$^1$Changes in temperature cause atomic vibrations that slowly randomize the direction of loops.
Also, a magnet can lose is magnetism by increasing it's temperature. When this  happens, at a point called the Curie temperature, a magnet will lose its strength completely.
A: In physics, “work” $W = \int \mathrm d\vec x \cdot \vec F$ is only done when the displacement $\mathrm d\vec x$ is nonzero. If the weight doesn’t move, no work is done.
Most people have a permanent magnet that’s been on their refrigerator for a year.  The energy cost is the same as keeping it on the shelf.
In a ferromagnetic material, the magnetized state is the “ground state.” An unmagnetized piece of iron can actually release energy by magnetizing, and you’d have to add energy to get it to de-magnetize again.
