INTERFACE TENSION IN 3-DIMENSIONAL SYSTEMS FROM FIELD-THEORY

In liquid mixtures or analogous binary systems at low temperatures the pure phases may coexist, separated by an interface. The interface tension vanishes according to σ = σ0(1-T/Tc)μ as the temperature T approaches the critical point from below. Similarly, the correlation length diverges as ξ = ξ0+(T/Tc - 1)-ν in the high-temperature region. For three-dimensional systems the dimensionless product R+ = σ0(ξ0+)2 is universal. We calculate its value in the framework of field theory in d = 3 dimensions without recourse to the ε{lunate}-expansion. The result R+ = 0.39 ± 0.03 is in agreement with experimental data. © 1990.