Heat Flow in the Extraordinary Phases of LiquidHe3

Abstract

In a heat-flow experiment at zero field we have found that the phase diagram of liquid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ below the second-order transition at $T_c$ divides into two regions. In one the heat flow is linear and enhanced by an amount predicted by a two-fluid model; the other shows nonlinearity, history dependence, and critical-velocity effects. The two are separated by a line of thermal-resistance discontinuities which extrapolates to what may be a polycritical point at the line $T_c$ and possibly to the "$B$" feature at the melting line.