AI 中文总结
该研究通过高质量单晶CeNiC2的压力依赖电阻率测量，发现其在Pc≈9.5-10 GPa附近呈现近各向同性量子临界输运，揭示价态涨落是相关临界散射的主要来源。
AI 中文摘要
多晶CeNiC2中已报道了压力诱导的超导电性和T线性电阻率，但取向平均效应使得临界散射的各向异性特征未得到解决。我们报告了高质量单晶沿各晶轴方向的压力依赖电阻率，这些单晶的剩余电阻率显著低于多晶样品，且最大起始Tc略高于多晶样品，使超导电性处于更纯净的输运 regime。在Pc≈9.5-10 GPa附近，正常态电阻率沿各轴均呈近T线性，拟合得到的剩余电阻率显著增强，超导电性形成窄圆顶。对于平行于b轴的电流，在施加于a轴和c轴、强度达9 T的磁场中，T线性正常态几乎保持不变；上临界场较大且仅呈中等各向异性。三个轴方向的共同演化确立了近各向同性的量子临界输运 regime，这与简单的低维自旋涨落图像不符，表明价态涨落是与超导圆顶相关的临界散射的主要来源。
英文摘要
Pressure-induced superconductivity and $T$-linear resistivity have been reported in polycrystalline CeNiC$_2$, but orientational averaging has left the directional character of the critical scattering unresolved. We report pressure-dependent resistivity of high-quality single crystals for current along each crystallographic axis. These crystals have substantially lower residual resistivity and a slightly higher maximum onset $T_c$ than the polycrystalline sample, placing superconductivity in a cleaner transport regime. Near $P_c \approx 9.5-10$ GPa, the normal-state resistivity becomes nearly $T$-linear along every axis, the fitted residual resistivity is strongly enhanced, and superconductivity forms a narrow dome. For $I \parallel b$, the $T$-linear normal state remains nearly unchanged in magnetic fields up to 9 T applied along $a$ and $c$; the upper critical field is large and only moderately anisotropic. The common evolution along all three axes establishes a nearly isotropic quantum-critical transport regime, inconsistent with a simple low-dimensional spin-fluctuation picture and implicates valence fluctuations as the leading source of critical scattering associated with the superconducting dome.
