Correction to: Nature Physics https://doi.org/10.1038/s41567-019-0651-0, published online 16 September 2019.

In the version of this Letter originally published online, the descriptions of the pink and purple curves in Fig. 2a were switched in the caption; the text should have read “The data are taken at zero applied field (purple) and with an in-plane magnetic field of 2 T (pink).” This has now been corrected in all versions.