Effect of the Pressure on the Splitting of the Superfluid Transition in 3He in Nematic Aerogel

Abstract

Here, we present the results of an investigation of how the pressure affects the splitting of the superfluid transition temperature in ³He in anisotropic aerogel. It is well known that boundary conditions significantly influence the properties of superfluid phases in aerogel. When aerogel strands are coated with a ⁴He layer in magnetic field, new phases, such as the polar, polar-distorted A (DA), polar-distorted B (DB), and \(\beta \) phases, become energetically favorable. In contrast, without this coating, the system tends to favor phases resembling the bulk A, B, and A₁ phases. Our earlier results showed a nonlinear dependence of the superfluid transition temperature splitting in pure ³He, but the range of nonlinearity did not match the theoretical predictions based on magnetic scattering effects. To further investigate this discrepancy, we performed measurements of the splitting under varying pressures for both pure ³He and with ⁴He coverage of the aerogel strands.