How long does it take a magnet to lose its magnetization?

Question

As we all know, a magnet has some magnetization that lets it attract other ferromagnetic materials but I was wondering how long it takes to lose this magnetization? Is it even possible or not?

Answer 1

This will depend highly on temperature and the material.

I could not find numbers quickly, but once heated above the Curie temperature a magnet will loose virtually all magnetization (as it will cease to be ferromagnetic). When heated close to the Curie temperature fluctuations will be strong enough to let the macroscopic magnetization decay.

But I guess at room temperature the decay rate will be very low, as it is exponentially suppressed (perhaps on the scale of millions of years). The energy scale is that of moving a Weiss domain boundary, and these will be locked by defects.

Microscopically, a ferromagnet will always be fully magnetized, only the macroscopic magnetization will cancel out, as the magnetic domains will point randomly in all directions.