Unconventional superconductivity driven by Kondo-destruction quantum criticality*

How quantum criticality affects superconductivity is a central issue in strongly correlated systems. Particularly pressing is for the beyond-Landau type quantum criticality, such as appearing in heavy fermion systems in the form of Kondo destruction [1]. This is exemplified by the heavy fermion superconductor CeRhIn₅, which has an antiferromagnetic quantum critical point (QCP) accompanied by a sharp Fermi surface reconstruction, and in which d-wave superconductivity develops with a high T_c [2]. Here we address the pairing instabilities near a Kondo destruction QCP by studying the Anderson lattice model using the Cluster Extended-DMFT approach [3]. For extreme Ising anisotropic case, the paring susceptibility is significantly enhanced near the QCP. Whereas for SU(2) symmetric case, we find superconducting order around the QCP [4]; T_c is comparably high as compared with the observation in CeRhIn₅ under optimal pressure. In both cases, we find the paring tendency to be stronger for the Kondo destruction type QCP than for the spin density wave type.
[1] Q. Si and F. Steglich, Science 329, 1161 (2010).
[2] T. Park et al., Nature 440,65 (2006);
[3] J. Pixley et al, PRB 91, 125127 (2015).
[4] A. Cai et al. (2018).