Temperature dependence of the order parameter of the polar phase of liquid 3He in nematic aerogel

Phase diagram of superfluid 3He in "nematically ordered" aerogel

Results of experiments with liquid 3He immersed in a new type of aerogel are described. This aerogel consists of Al2O3 strands which are nearly parallel to each other, so we call it as a "nematically ordered" aerogel. At all used pressures a superfluid transition was observed and a superfluid phase diagram was measured. Possible structures of the observed superfluid phases are discussed.

Nematic--to--Smectic-A Transition in Aerogel

We study a model for the Nematic--Smectic-A (NA) transition in aerogel, and find that even arbitrarily weak quenched disorder (i.e., low aerogel density) destroys translational (smectic) order. Ignoring elastic anharmonicities, but keeping anharmonic couplings to disorder, leads to the prediction that there is no ``Bragg glass'' phase in this system: it is riddled with dislocation loops induced by the quenched disorder. Orientational (nematic) order is destroyed as well, as is the thermodynamically sharp NA transition, in agreement with recent experimental results.

Anisotropic 2D Larkin-Imry-Ma state in polar distorted ABM phase of 3He in "nematically ordered" aerogel

We present results of experiments in superfluid phases of 3He confined in aerogel which strands are nearly parallel to one another. High temperature superfluid phases of 3He in this aerogel (ESP1 and ESP2) are chiral phases and have polar distorted ABM order parameter which orbital part forms 2D Larkin-Imry-Ma state. We demonstrate that this state can be anisotropic if the aerogel is squeezed in direction transverse to the strands. Values of this anisotropy in ESP1 and ESP2 phases are different, what leads to different NMR properties.

向列 aerogel 中超流 3He 极性相的稳定性研究

On the Stability of the Polar Phase of Superfluid 3He in Nematic Aerogels

该研究探讨向列 aerogel 中超流 3He 极性相在磁性杂质散射微扰下的稳定性，提出 p 波散射势模型并求解 Gor'kov 自洽方程，发现微扰同时破坏轴向与时间反演对称性时极性畸变 A 相转变温度最高，结果与现有实验数据相关。

The distorted axi-planar superfluid phase of $^3$He in the "nematically ordered" aerogel

Stimulated by the results of NMR experiments with superfluid $^3$He in "nematically ordered" aerogel [1] we report on the results of phenomenological analysis of stability of different phases of superfluid $^3$He subjected to a strong homogeneous uniaxial anisotropy. On a basis of this analysis we suggest a form of the order parameter for the new ESP2 phase observed in the quoted experiments. In the weak coupling limit the suggested order parameter approaches that of the axi-planar phase. We discuss a possible experimental check of the proposed identification of the new phase.

Analog of Anderson theorem for the polar phase of liquid 3He in nematic aerogel

It is shown that if impurities in superfluid 3He have form of infinitely long non-magnetic strands, which are straight, parallel to each other and reflect quasi-particles specularly, the temperature of transition of liquid 3He from the normal into the polar phase coincides with that for the bulk liquid without impurities. Magnetic scattering lowers transition temperature for the polar phase in analogy with the conventional superconductors. These results are discussed in connection with the recent experimental findings.