Critical Casimir effect and wetting by helium mixtures

Sebastien Balibar (1) , Tomohiro Ueno (1) , Takao Mizusaki (1) , Frederic Caupin (1) , Etienne Rolley (1)

1 LPS - Laboratoire de Physique Statistique de l'ENS

We have measured the contact angle of the interface of phase-separated$^{3}$He-$^{4}$He mixtures against a sapphire window. We have foundthat this angle is finite and does not tend to zero when thetemperature approaches $T_t$, the temperature of the tri-criticalpoint. On the contrary, it increases with temperature. This behavioris a remarkable exception to what is generally observed near criticalpoints, i.e. "critical point wetting''. We propose that it is aconsequence of the "critical Casimir effect'' which leads to aneffective attraction of the $^{3}$He-$^{4}$He interface by thesapphire near $T_{t}$.

Mots clés: wetting; Casimir; critical phenomena; helium

Domaines: Autre [cond-mat.other]

Sebastien Balibar, Tomohiro Ueno, Takao Mizusaki, Frederic Caupin, Etienne Rolley. Critical Casimir effect and wetting by helium mixtures. Physical Review Letters, 2003, 90, pp.116102. ⟨hal-00000255⟩