论文标题
点点节点和非统一三重组的方向通过UTE2中的易于轴磁化调谐
Orientation of point nodes and nonunitary triplet pairing tuned by the easy-axis magnetization in UTe2
论文作者
论文摘要
已经通过特定的热$ c（t，h，ω）$测量值研究了位于铁磁量子关键性附近的新型铀超导体UTE $ _2 $的间隙结构。其Angular $ω（ϕ，θ）$变化显示了一个特征性的肩部异常，其局部最小值在$ h \ \ parallel a $ a $在$ ab $和$ ac $ planes中旋转的中等磁场。基于理论计算，这些功能可以归因于沿$ a方向超导间隙中的点节点的存在。在沿易于磁通$ a $轴的田间方向下，观察到了低磁场上临界场的异常温度依赖性，并观察到$ c（h）$中的凸向下曲率。这些异常行为可以基于与平等旋转配对的非单身三胞胎状态模型进行解释，其$ t _ {\ rm c} $通过沿$ a $ axis的磁化来调整。从这些结果中，UTE $ _2 $的间隙对称性很可能由$ d（k）=（b + ic）的向量顺序参数（k_b + ik_c）$描述。
The gap structure of a novel uranium-based superconductor UTe$_2$, situated in the vicinity of ferromagnetic quantum criticality, has been investigated via specific-heat $C(T,H,Ω)$ measurements in various field orientations. Its angular $Ω(ϕ,θ)$ variation shows a characteristic shoulder anomaly with a local minimum in $H \parallel a$ at moderate fields rotated within the $ab$ and $ac$ planes. Based on the theoretical calculations, these features can be attributed to the presence of point nodes in the superconducting gap along the $a$ direction. Under the field orientation along the easy-magnetization $a$ axis, an unusual temperature dependence of the upper critical field at low fields together with a convex downward curvature in $C(H)$ were observed. These anomalous behaviors can be explained on the basis of a nonunitary triplet state model with equal-spin pairing whose $T_{\rm c}$ is tuned by the magnetization along the $a$ axis. From these results, the gap symmetry of UTe$_2$ is most likely described by a vector order parameter of $d(k)=(b + ic)(k_b + ik_c)$.
