Continued investigations of the time reversal symmetry broken in the superconducting state of the caged compounds RE5Ir6Sn18 (RE = Y and Lu)

High quality single crystals RE5Ir6Sn18 (RE = Y, and Lu) have been successfully growth by flux method. These caged type compound reveal superconductivity below Tc = 2 K, and 2.9 K for RE = Y, and Lu respectively. It had been reported that R5Rh6Sn18 (R = Sc, Y, Lu), which exhibit superconductivity at 5 K (Sc), 3 K (Y) and 4 K (Lu), show intrigue time-reversal-symmetry broken in the superconductive state. It is interesting to compare the SR results of Y5Ir6Sn18, and Lu5Ir6Sn18, which possess different shells but same number of d electrons and different Tc, to investigate time-reversal-symmetry broken mechanisms in RE5Ir6Sn18 and their related dynamics.(Due to the instable beams and the issues of HELIOX, we could not complete the experiments in the last beamtime allocated)

采用助熔剂法成功制备了高质量稀土元素（Rare Earth, RE）基RE₅Ir₆Sn₁₈（RE=Y、Lu）单晶体。该类笼型化合物分别在临界转变温度Tc=2 K（对应RE=Y）、2.9 K（对应RE=Lu）时表现出超导特性。已有研究报道，R₅Rh₆Sn₁₈（R=Sc、Y、Lu）分别在5 K（Sc）、3 K（Y）、4 K（Lu）时呈现超导性，且其超导态下存在显著的时间反演对称性破缺现象。对比Y₅Ir₆Sn₁₈与Lu₅Ir₆Sn₁₈的μ子自旋弛豫/共振（Muon Spin Relaxation/Resonance, μSR）结果具有重要研究价值：这两种化合物拥有不同的壳层结构，但d电子数一致且临界转变温度Tc存在差异，借此可深入探究RE₅Ir₆Sn₁₈体系中的时间反演对称性破缺机制及其相关动力学过程。（由于束流不稳定及HELIOX装置相关问题，我们未能在获批的上一次束流实验时段内完成全部实验。）