2021/09/28 by ElMassalami, M., Castro, P. B., Neto, M. B. Silva
#FOS: Physical sciences #Strongly Correlated Electrons (cond-mat.str-el) #Superconductivity (cond-mat.supr-con)
paper · doi:10.48550/arxiv.2109.14032
Extensively reported experimental observations indicate that on varying pressure (p) within the T-p phase diagram of most quantum critical heavy fermion (HF) superconductors, one identifies a cascade of distinct electronic states which may be magnetic, of Kondo-type, non-conventional superconducting, Fermi Liquid (FL), or non-FL character. Of particular interest to this work is the part of the phase diagram lying below a specific phase boundary, T*FL(p*), across which the transport and thermodynamic properties switch over from non-FL into FL behavior. Remarkably, this nontrivial manifestation of FL phase is accompanied by (i) the characteristic ρo + AT2 dependence (ρo = residual resistivity), (ii) a superconductivity below Tc ≤ T*FL(p*), and (iii) a universal scaling of Tc and A: ln\fracTcθ∝ A-(1)/(2) (θ = characteristic energy scale). We consider that such features are driven by a fluctuation-mediated electron-electron scattering channel with the mediating quasiparticles being either spin fluctuations [Mathur et al., Nature 394,39 (1998)] or valence fluctuations [Miyake and Watanabe, Phil. Mag. 97, 3496 (2017)] depending on the character of the neighboring instability. On adopting such a scattering channel and applying standard theories of Migdal-Eliashberg (superconductivity) and Boltzmann (transport), we derive analytic expressions that satisfactorily reproduce the aforementioned empirical correlations in these heavy fermion superconductors.