Nature, Published online: 19 March 2025; doi:10.1038/s41586-025-08725-5Itinerant magnetism in rhombohedral multilayer graphene shows a large excess entropy from magnetic fluctuations above its critical temperaturetypically only associated with local momentswhich implies the decoupling of charge and isospin degrees of freedom, and results in the isospin Pomeranchuk effect.