Sixfold enhancement of superconductivity in a tunable electronic nematic system

• Published in: Nature physics Vol. 16; no. 3; pp. 346 - 350
• Main Authors: Eckberg, Chris, Campbell, Daniel J., Metz, Tristin, Collini, John, Hodovanets, Halyna, Drye, Tyler, Zavalij, Peter, Christensen, Morten H., Fernandes, Rafael M., Lee, Sangjun, Abbamonte, Peter, Lynn, Jeffrey W., Paglione, Johnpierre
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 2020; Nature Publishing Group; Nature Publishing Group (NPG)
• Subjects: 639/766/119/1003; 639/766/119/2795; Absolute zero; Atomic; Charge density waves; Classical and Continuum Physics; Complex Systems; Condensed Matter Physics; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Cuprates; Fluctuations; High temperature; High temperature superconductors; Mathematical and Computational Physics; Molecular; Nickel; Nickel compounds; Optical and Plasma Physics; Phase transitions; Physics; Physics and Astronomy; Strontium; Superconductivity; Theoretical; Transition temperature; Transition temperatures
• ISSN: 1745-2473; 1745-2481
• DOI: 10.1038/s41567-019-0736-9

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− x Sr x Ni 2 As 2 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. Transport measurements show that nematic fluctuations near a phase transition increase the temperature at which superconductivity occurs by a factor of nearly six. This happens in a non-magnetic nickel-based compound.