Reading the article it seems this research is about Amonton's first law which is about the way friction increases with load. This experiment shows that in certain scenarios the friction can be low when the distance is close or far but at a medium distance (not sure the exact distances here) the friction increases thus breaking Amontons' first law.

[–] suff@piefed.social 3 points 6 days ago (1 children)

Although the magnetic interaction, i.e. the normal load between the two layers monotonically decreases with increasing h, 〈Fₓ〉exhibits a clear peak around h₀ = 9 mm. This is in strong contradiction with Amonton's empirical first law, which claims that sliding friction is proportional to the load ^33^.

[–] teft@piefed.social 0 points 6 days ago (1 children)

Oh wow a lot farther than i was thinking. I had guessed submillimeter. Thanks for the link to the paper.

[–] suff@piefed.social 1 points 6 days ago

Magnets such as those NdFeB magnets (N35 grade with nickel surface coating, HKCM Article No. 9963-73617 and HKCM Article No. 9962-61814) weren't tested back then, I guess.

[–] kata1yst@sh.itjust.works 5 points 1 week ago

Ah! Thank you for the correction. Much appreciated!