NMR study of Multipole order and fluctuation in rare-earth compounds

一般情况下，多极序的转变温度较低，测量系统降到极低温度是必不可少的。在这项研究中，我们成功地利用^3He制冷机制作了一个手工核磁共振测量系统，其温度可低至0.5 K。我们对（Tm^<0.5>Yb^<0.5>）B_6进行了^<11>B核磁共振测量，讨论了多极序的可能性。然而，发现相变的起源不是多极序，而是磁偶极序。我们还研究了CeRu_2Al_<10>表现出独特的相变，并进行了单晶制备、许多宏观测量和^<27>Al NMR。

Generally the transition temperature of the multipole order is low, and measuring system down to very low temperature is indispensable. In this study, we succeeded in making a handmade NMR measuring system by using ^3He refrigerator which can be reaching down to 0.5 K. We performed the ^<11>B NMR measurement on (Tm^<0.5>Yb^<0.5>)B_6 in which a possibility of the multipole order was discussed. However, it was revealed that the origin of the phase transition is not a multipole but a magnetic dipole order. We also studied about CeRu_2Al_<10> showing an unique phase transition, and performed single crystal preparation, many macroscopic measurement, and ^<27>Al NMR.