Universality of TricriticalHe3-He4Mixtures under Pressure

Abstract

The phase diagram of liquid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ mixtures in the vicinity of the tricritical point has been determined at saturated vapor pressure and at 22.6 bars, close to solidification. Neither the critical exponent $\beta$ nor the slopes of the phase-separation curve change with pressure indicating universal behavior of the tricritical ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ system.