The electronic nematic phase—in which electronic degrees of freedom lower the crystal rotational symmetry—is commonly observed in high-temperature superconductors. However, understanding the role of nematicity and nematic fluctuations in Cooper pairing is often made more complicated by the coexistence of other orders, particularly long-range magnetic order. Here we report the enhancement of superconductivity in a model electronic nematic system that is not magnetic, and show that the enhancement is directly born out of strong nematic fluctuations associated with a quantum phase transition. We present measurements of the resistance as a function of strain in Ba_1−xSr_xNi₂As₂ to show that strontium substitution promotes an electronically driven nematic order in this system. In addition, the complete suppression of that order to absolute zero temperature leads to an enhancement of the pairing strength, as evidenced by a sixfold increase in the superconducting transition temperature. The direct relation between enhanced pairing and nematic fluctuations in this model system, as well as the interplay with a unidirectional charge-density-wave order comparable to that found in the cuprates, offers a means to investigate the role of nematicity in strengthening superconductivity.

通常在高温超导体中观察到电子向列相，其中电子自由度降低了晶体的旋转对称性。但是，由于其他阶次（尤其是远距离磁阶）的共存，通常更难理解向列性和向列波动在库珀配对中的作用。在这里，我们报告了在非磁性的模型电子向列系统中超导性的增强，并表明这种增强直接源自与量子相变相关的强烈向列波动。我们介绍了在Ba _{1− x} Sr _x Ni ₂ As _2中电阻作为应变函数的测量结果表明锶替代在该系统中促进了电子驱动的向列顺序。此外，将该阶数完全抑制到绝对零温度会导致配对强度增强，这可以通过超导转变温度的六倍增加来证明。在该模型系统中，增强配对与向列波动之间的直接关系，以及与铜酸盐中可比的单向电荷密度波阶的相互作用，为研究向列性在增强超导性中的作用提供了一种手段。