Experimental study of free surface of superfluid 3He

在这个项目中，我们澄清了在100mK以下液体3He的表面张力与温度的关系几乎是熄灭的(在0到100mK之间是平坦的)，并且在100mK附近有一个很小的峰。表面张力随温度变化的主导项是T^2，T^2项的系数很小是由于表面附近的费米能密度变小，然后随着密度的减小而变大，当T^2系数变得很小时，下一高阶项变得重要。下一项应取决于强关联费米液体(^3He)的模型。我们采用了描述液态~3He的三泽模型作为准偏磁模型。在这一理论中，下一个领先项是Ct^4LN(T/T^*)。通过适当的拟合，我们可以很好地再现实验中观察到的小的最大值，从而可以从低温下表面张力的精确测量中推断出关于液体3He的一些重要信息。我们在超流3He表面的零声反射实验中也取得了一些进展。不幸的是，我们不能在项目期间进行实验，但第一个实验很快就会完成。

In this project we have clarified that the temperature dependence of the surface tension of liquid 3He below 100 mK is almost quenched (flat between 0 and 100 mK) and also there is a very small peak around 100 mK.The experimental results were analyzed based on the assumption that the local entropy density picture is correct. The leading term of the temperature dependence of surface tension is T^2 and the very small coefficient of T^2 term is the result that the Fermi energy density near the surface becomes smaller than that of bulk liquid and then gets much bigger as the density decreases more.As the coefficient of T^2 becomes very small, the next higher order term becomes important. The next term should be dependent on the model of the strongly correlated Fermi-liquid (^3He). We adopted the Misawa's model which describes the liquid ^3He as the nearly meta-magnetic model. In this theory the next leading term is cT^4ln(T/T^*). By a suitable fitting, we could reproduce the small maximum observed in the experiment perfectly.Thus we could deduce some important information on liquid 3He from the precise measurement of surface tension in the low temperature.We also have made some progress in the experiment on zero sound reflection at the superfluid ^3He surface. Unfortunately we could not perform the experiment during the project period but the first experiment will be done pretty soon.