Finite-Size Scaling and Universality of the Thermal Resistivity of Liquid ⁴He near T_λ

We present measurements of the thermal resistivity $\rho(t,P,L)$ near the superfluid transition of $^4$He at saturated vapor pressure and confined in cylindrical geometries with radii $L=0.5$ and 1.0 $\mu$m ($t\equiv T/T_\lambda(P) - 1$). For $L = 1.0 \mu$m measurements at six pressures $P$ are presented. At and above $T_\lambda$ the data are consistent with a universal scaling function $F=(L/\xi_0)^{x/\nu}(R/R_0)$, $X= (L/\xi_0)^{1/\nu}t$ valid for all $P$ ($R_0$ and $x$ are the pressure-dependent amplitude and effective exponent of the bulk resistivity $R$ and $\xi = \xi_0 t^{-\nu}$ is the correlation length).