Pierre Weiss

Pierre-Ernest Weiss (25 March 1865, Mulhouse – 24 October 1940, Lyon) was a French physicist specialized in magnetism. He developed the domain theory of ferromagnetism in 1907. Weiss domains and the Weiss magneton are named after him. Weiss also developed the molecular or mean field theory, which is often called Weiss-mean-field theory, that lead to the discovery of the Curie-Weiss law. Alongside Auguste Picard, Pierre Weiss is considered one of the first discoverers of the magnetocaloric effect in 1917.