Kawka, AdelaVennes, StephaneAllard, Nicole F.Leininger, T.Gadéa, F. X.2024-03-082024-03-080035-8711http://hdl.handle.net/1885/315821We present an analysis of photometric, spectroscopic, and spectropolarimetric data of the nearby, cool, magnetic DZ white dwarf PM J08186−3110. High-dispersion spectra show the presence of Zeeman splitted spectral lines due to the presence of a surface average magnetic field of 92 kG. The strong magnesium and calcium lines show extended wings shaped by interactions with neutral helium in a dense, cool helium-rich atmosphere. We found that the abundance of heavy elements varied between spectra taken 10 years apart but we could not establish a time-scale for these variations; such variations may be linked to surface abundance variations in the magnetized atmosphere. Finally, we show that volume-limited samples reveal that about 40 per cent of DZ white dwarfs with effective temperatures below 7000 K are magnetic.application/pdfen-AU© 2020 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society202110.1093/mnras/staa34212022-10-16