Hysteresis has been observed in de Haas-van Alphen measurements of the Condon domains in silver, and it shows the first-order nature of the transition to the domain state. The hysteresis, and thus the first-order nature, is manifested in a nonlinear effect where a double-valued response of the amplitude with the applied external field is observed.
@article{arxiv.cond-mat/0310627,
title = {Domain State Occurring in the de Haas-van Alphen Effect in Silver},
author = {J. L. Smith and J. C. Lashley},
journal= {arXiv preprint arXiv:cond-mat/0310627},
year = {2009}
}