标题： 超导Pr1-xCexPt4Ge12中的时间反演对称性破缺 显示英文标题

标题： Broken Time Reversal Symmetry in Superconducting Pr1-xCexPt4Ge12

摘要： 我们报告了在填充-skutterudite 超导体~Pr$_{1-x}$Ce$_{x}$Pt$_4$Ge$_{12}$，$x = 0$， 0.07, 0.1 和 0.2 上进行的零场μ子自旋弛豫实验，以研究Ce掺杂对超导态中破坏时间反演对称性（TRS）的影响。 在这些合金中，时间反演对称性的破坏由超导转变温度以下出现的自发静态局部磁场~$B_s$来表明。 我们发现，在$x \approx 0.4$处，$B_s$随着$x$和$\to 0$的增加而线性减小，接近超导性不再被观察到的浓度。 该(Pr,Ce)Pt$_4$Ge$_{12}$和同结构的(Pr,La)Os$_4$Sb$_{12}$合金系列均表现出具有破缺TRS的超导性，在两者中，$B_s$的减少与Pr浓度的减少成比例。这表明Pr-Pr晶位相互作用是导致TRS破缺的原因\@ 。 两个合金系列的不同之处在于，掺La的合金在所有La浓度下都是超导的，这表明在(Pr,Ce)Pt$_4$Ge$_{12}$中，Ce掺杂引起的对电子对破坏抑制了超导性。 对于所有$x$，动态μ子自旋弛豫率在超导状态下有所降低。 这可能是由于传导电子引起的Korringa弛豫，而超导能隙的打开会减少这种弛豫。 显示英文摘要

摘要： We report results of zero-field muon spin relaxation experiments on the filled-skutterudite superconductors~Pr$_{1-x}$Ce$_{x}$Pt$_4$Ge$_{12}$, $x = 0$, 0.07, 0.1, and 0.2, to investigate the effect of Ce doping on broken time-reversal symmetry (TRS) in the superconducting state. In these alloys broken TRS is signaled by the onset of a spontaneous static local magnetic field~$B_s$ below the superconducting transition temperature. We find that $B_s$ decreases linearly with $x$ and $\to 0$ at $x \approx 0.4$, close to the concentration above which superconductivity is no longer observed. The (Pr,Ce)Pt$_4$Ge$_{12}$ and isostructural (Pr,La)Os$_4$Sb$_{12}$ alloy series both exhibit superconductivity with broken TRS, and in both the decrease of $B_s$ is proportional to the decrease of Pr concentration. This suggests that Pr-Pr intersite interactions are responsible for the broken TRS\@. The two alloy series differ in that the La-doped alloys are superconducting for all La concentrations, suggesting that in (Pr,Ce)Pt$_4$Ge$_{12}$ pair-breaking by Ce doping suppresses superconductivity. For all $x$ the dynamic muon spin relaxation rate decreases somewhat in the superconducting state. This may be due to Korringa relaxation by conduction electrons, which is reduced by the opening of the superconducting energy gap.