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

固体3 He显示出量子固体特有的有趣的核磁性质。许多实验结果已经确定，体心立方固体^3 He中存在三个磁相：温度高于lmK的顺磁相（PP）、温度低于lmK的低场反铁磁相（LFP）和高场磁有序相（HFP）磁场大于0.4T。从PP或HFP到LFP的转变已被澄清为一级。然而，HFP-PP转变的顺序仍然存在争议。通过30摩尔Cu的去磁来冷却电池。核级的最低温度和热漏分别为8luK和48 OpW。这个核阶段的温度保持在1 mK以下约两个月。在磁场中测量了^3He的熔化压力。固体^3He的相变是由温度和磁场扫描过程中熔化曲线的异常决定的。用这样确定的B-T相图，三相点附近的转变线的斜率表明顺磁到高场相变的一级转变。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。还得到了磁场中自旋波的速度。

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.