Quasi-particle scattering with polarized nuclei on ion cluster in liquid ^3He

液体中的离子，根据其电荷符号的不同，有不同的结构。一个正离子，即所谓的“雪球”，定域了他在表面上的自转。相反，负离子是电子被困在其中的气泡。在100mK以下的低温下，离子的迁移率由朗道准粒子的散射决定，因此这种情况类似于金属中的杂质散射。在正离子情况下，定域~3He自旋与准粒子在离子表面的交换散射似乎起到了重要作用。为了研究这种效应，在正常液体中，阳离子的迁移率。在温度低至3MK的情况下，测量了高达15T的外部磁场对他的影响。它确实取决于20巴以上高压下的磁场。尤其是在3.2MK时，随着电场的增大，它有一个随压力变化的小而宽的峰，然后急剧下降约30%。另一方面，在20mK时，在相同的压强范围内，随着磁场的增加，磁化强度单调减小。相反，29bar处的负离子迁移率与温度和磁场无关。这些事实表明，^3He准粒子与“雪球”之间存在交换作用。然而，这些结果过于复杂，目前我们还无法阐明其作用机制。在较宽的参数范围内，还需要进一步的系统实验，迫切需要一种新的理论处理来理解强磁场下的正离子迁移率。

Ion in liquid ^3He has a different structure depending on its sign of the charge. A positive ion, so called a "snowball", has localized ^3He spins on the surface. On the contrary a negative ion is a bubble in which an electron is trapped. Ion mobility at low temperatures below 100 mK is determined by scattering with Landau quasi-particles, hence the situation resembles an impurity scattering in metals. In the case of positive ion, the exchange scattering of localized ^3He spins on the ion surface with quasi particles seems to play an important role. To investigate such an effect, positive ion mobility in normal liquid. ^3He has been measured as a function of external magnetic fields up to 15 T at temperatures down to 3 mK. It does depend on the magnetic field at high pressures above 20 bars. Especially at 3.2 mK, it has a pressure dependent small and broad peak followed by a drastic decrease of about 30 % with increasing the field. On the other hand, at 20 mK, a monotonous decrease with increasing the magnetic field has been observed in the same pressure region. In contrast negative ion mobility at 29 bar is found to be independent of both temperature and magnetic field. These facts indicate that there exists an exchange interaction between ^3He quasi-particle and "snowball". However the results are too complicated for us to clarify the mechanism at present. Further systematic experiments should be made in the wide range of parameters, and a new theoretical treatment is eagerly desired to understand the positive ion mobility under high magnetic fields.