Research of Nuclear Magnetic Order of bcc Solid 3He in Magnetic Field.

固体3He显示出量子固体特有的有趣的核磁特性。许多实验结果表明，bcc固体^3He中存在三种磁相：温度高于lmK时的顺磁相（PP），温度低于lmK时的低场反铁磁相（LFP），以及场大于0.4T时的高场磁有序相（HFP）。从PP或HFP到LFP的转变已被澄清为一级。然而，HFP-PP过渡的顺序仍然存在争议。用Cu （30mol）消磁冷却电池。核段最低温度为8luK，热泄漏量为48OpW。这一核阶段将温度维持在1mK以下约两个月。测量了^3He在磁场中的熔化压力。在温度和磁场扫描过程中，熔化曲线的异常阻止了固体^3He的相变。由此确定的B-T相图，三相点附近的过渡线斜率表明顺磁相变到强场相变的一级转变。然而，在我们的实验精度范围内，没有观察到任何潜热的痕迹。得到了自旋波在磁场中的速度。

Solid 3He shows interesting nuclear magnetic properties which are particular to the quantum solid. Many experimental results have established that three magnetic phases exist in bcc solid ^3He:a paramagnetic phase (PP) for temperatures higher than lmK, a low field antiferromagnetic phase (LFP) for temperatures lower than lmK, and a high field magnetically ordered phase (HFP) for field greater than 0.4T. The transitions to the LFP from the PP or the HFP have been clarified as first order. However, the order of the HFP-PP transition is still controversial. The cell was cooled by the demagnetization of Cu, 30 moles. The minimum temperature and the heat leak of nuclear stage were 8luK and 48OpW, respectively. This nuclear stage maintains temperature less than 1mK for about two months. The melting pressure of ^3He was measured in magnetic field. The phase transitions of solid ^3He were deter mined by the anomaly of the melting curves during the temperature and the magnetic field sweep. With thus determined B-T phase diagram, the slope of the transition line near the triple point suggests the first order transition of the paramagnetic to the high field phase transition. However, any trace of thelatent heat was not observed within our experimental accuracy. The spin wave velocity in magnetic field was also obtained.