Second-sound velocity and superfluid density in3He-4He mixtures near superfluid transition points?Applicability of universality and scaling laws

Abstract

From second-sound velocity measurements, superfluid densities near superfluid transition points were determined in 3 He- 4 He mixtures under saturated vapor pressure. The critical exponent of the superfluid density thus obtained increases about 15% with increasing 3 He concentration up to 40 mole percent, which contradicts the universality concept. Furthermore, the critical exponents obtained here and the exponents of the specific heat do not satisfy the scaling laws. A new concept of universality is introduced and discussed.