论文标题
时间逆转不变的单间隙超导性，上限临界场大于nbir $ _2 $ b $ _2 $大于保利限制
Time reversal invariant single gap superconductivity with upper critical field larger than Pauli limit in NbIr$_2$B$_2$
论文作者
论文摘要
最近，具有非中心晶体结构的化合物引起了人们的广泛关注，以提供丰富的操场来寻找非常规的超导性。 Nbir $ _2 $ b $ _2 $是此类材料的新成员，其材料具有低于$ t _ {\ rm c} = 7.3（2）$ 〜K，超过Pauli限制的高临界场。在这里，我们报告了MUON自旋旋转（$μ$ SR）实验，以探测该化合物中有效磁穿透深度的温度和场依赖性。我们的横向场 - $μ$ SR的结果表明，完全倾斜的$ s $ - 波超导体。此外，高场运输测量值还补充了上临界场的估计高值。值得注意的是，比率$ t _ {\ rm c} $/$/$λ^{ - 2}（0）$ nbir $ _2 $ _2 $ b $ _2 $（$ \ sim $ 2）与非常规超导体的比率可比。零场$μ$ $ SR数据显示，在$ t _ {\ rm c} $之上和低于$ t的muon旋转放松率没有显着变化，证明时间反向对称性在超导状态下保留。提出的结果将刺激理论研究，以在这个独特的非中性对称系统中对超导性的起源进行微观理解。
Recently, compounds with noncentrosymmetric crystal structure have attracted much attention for providing a rich playground in search for unconventional superconductivity. NbIr$_2$B$_2$ is a new member to this class of materials harboring superconductivity below $T_{\rm c} = 7.3(2)$~K and very high upper critical field that exceeds Pauli limit. Here we report on muon spin rotation ($μ$SR) experiments probing the temperature and field dependence of effective magnetic penetration depth in this compound. Our transverse-field -$μ$SR results suggest a fully gaped $s$-wave superconductvity. Further, the estimated high value of upper critical field is also supplemented by high field transport measurements. Remarkably, the ratio $T_{\rm c}$/$λ^{-2}(0)$ obtained for NbIr$_2$B$_2$ ($\sim$2) is comparable to those of unconventional superconductors. Zero-field $μ$SR data reveals no significant change in the muon spin relaxation rate above and below $T_{\rm c}$, evincing that time-reversal symmetry is preserved in the superconducting state. The presented results will stimulate theoretical investigations to obtain a microscopic understanding of the origin of superconductivity with preserved time reversal symmetry in this unique noncentrosymmetric system.
