First observation of ferromagnetism and ferromagnetic domains in a liquid metal

Miniaturized electromagnetic levitation has been used to undercool a liquid Co80Pd20 alloy below the Curie temperature TC(l)=1257 K of the liquid state. The magnetization of the undercooled liquid sample has been measured as a function of temperature using a modified Faraday balance. Below TC(l), the magnetization of the liquid metal shows a plateau in the weak external field of μ0Hz=5.6 mT. The effect is comparable to the behaviour of the corresponding solid phase, indicating the onset of spontaneous magnetization with ferromagnetic domains. TC(l) is about 20 K lower than the Curie temperature of the solid phase TC(s). (orig.)