Study of magnetism and superconductivity in trans uranium compounds

我们已经准备了专门的实验室来处理具有高放射性的反式铀化合物。我们需要专门的仪器来测量反式铀化合物。我们需要金属Np来制造Np金属间化合物。从NpO_2开始，采用汞齐法。为此，我们制作了一种特殊的玻璃池。我们已经成功地制造了1克的Np金属。利用这种金属，我们已经制作了Np 115化合物的单晶样品。在这些单晶样品中，已进行磁化率，比热和X射线衍射测量来表征物理性质。晶体结构确定为115型，并测定了磁性转变温度。用中子衍射法测定了有序态的自旋结构。为了研究八极有序化合物NpO_2，制备<17>了富氧的NpO_2单晶样品。~ 1 <17>O-NMR测量表明，有序态的内场很小，表明出现了八极有序.我们成功地制备了单晶Pu化合物：Tc= 9 K的新超导体PuRhGa_5.使用该样品，基本的超导性能，如各向异性的HC 2。对高质量的PuRhGa_5单晶样品进行了自旋-晶格弛豫时间T_1和Knight位移的测量。在超导态，1/T_1没有相干峰，但遵循T^3定律，表明具有各向异性超导带隙的非常规超导性。观察到的Knight位移在T_c以下的减小证实了自旋单重态超导态的存在

We have prepared special labs for treatments of trans-uranium compounds which have high radio activity. We need special apparatus to measure the trans-uranium compounds. We need metal Np to make Np intermetallic compounds. We have used amalgam method stating from NpO_2. For that method we have made a special glass cell. We have succeeded to make 1g of Np metal. Using this Np metal, we have made single crystal samples of Np 115 compounds. In these single crystal samples, magnetic susceptibility, specific heat and X-ray diffraction measurements have been performed to characterize physical properties. Crystal structure is determined as 115 one, and magnetic transition temperature is determined. Using neutron diffraction, spin structure of ordered states are determined.For studying octupolar ordering compound NpO_2, single crystal ^<17>O enriched NpO_2 samples have been made. From ^<17>O-NMR measurements, internal field in the ordered state is quite small, indicating the appearance of octupolar ordering.We have succeeded to make single crystal Pu compound : new superconductor PuRhGa5 with Tc=9K. Using this sample, basic superconducting properties like anisotropy of Hc2. Spin-lattice relaxation time T_1 and Knight shift measurements on a high-quality single crystal sample of PuRhGa_5 are performed. In the superconducting state, 1/T_1 shows no coherence peak, but follows a T^3 law, suggesting unconventional superconductivity with an anisotropic superconducting gap. An observed decrease of the Knight shift below T_c confirms a spin singlet superconducting state