Sixfold Enhancement of Superconductivity in a Tunable Electronic Nematic System
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 Ba11-xSrxNi2As2 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.
C. Eckberg and D. J. Campbell and T. Metz and J. Collini and H. Hodovanets and T. Drye and P. Zavalij and M. H. Christensen and R. M. Fernandes and For full list of authors, see publisher's website., "Sixfold Enhancement of Superconductivity in a Tunable Electronic Nematic System," Nature Physics, vol. 16, no. 3, pp. 346 - 350, Nature Research, Mar 2020.
The definitive version is available at https://doi.org/10.1038/s41567-019-0736-9
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01 Mar 2020