Tail states in disordered superconductors with magnetic impurities: the unitarity limit

Excellent fits of the tunneling density of states in disordered superconductors can be often achieved making use of the phenomenological Dynes formula. However, no consistent derivation of this formula has been available so far. The Dynes formula can be interpreted by the simplest causal frequency-dependent gap function ∆(ω) with a vanishing gap at the Fermi level. Here we show, within the coherent potential approximation, that precisely such gap function describes superconductors with a Lorentzian distribution of pair-breaking fields and arbitrary potential disorder. We predict spectral and thermodynamic properties of such superconductors.

mentioning

confidence: 99%

Microscopic interpretation of the Dynes formula for the tunneling density of states

Herman¹,

Hlubina²

2016

“…Now it is instructive to compare our results for the density of states with the results of the instanton analysis [31,35]. The density of states due to instantons near the band gap E g is given as…”

Section: The Density Of Statesmentioning

confidence: 84%

“…It is convenient to parametrize the spectral angle as θ = π/2+iψ. Without renormalization (t = 0), the angle ψ(E) should be determined from equation F E (ψ) = 0, where [17,20,21,31]…”

Section: Density Of Statesmentioning

confidence: 99%

See 1 more Smart Citation

Magnetic disorder in superconductors: Enhancement by mesoscopic fluctuations

Burmistrov

Skvortsov

2018

We study the density of states (DOS) and the transition temperature Tc in a dirty superconducting film with rare classical magnetic impurities of an arbitrary strength described by the Poissonian statistics. We take into account that the potential disorder is a source for mesoscopic fluctuations of the local DOS, and, consequently, for the effective strength of magnetic impurities. We find that these mesoscopic fluctuations result in a non-zero DOS for all energies in the region of the phase diagram where without this effect the DOS is zero within the standard mean-field theory. This mechanism can be more efficient in filling the mean-field superconducting gap than rare fluctuations of the potential disorder (instantons). Depending on the magnetic impurity strength, the suppression of Tc by spin-flip scattering can be faster or slower than in the standard mean-field theory. arXiv:1703.02126v2 [cond-mat.supr-con]

“…S = S σ + S mag . For rare magnetic impurities the latter can be written as a sum over contributions of individual magnetic impurities [24]:…”

Section: Finkel'stein Nonlinear Sigma Modelmentioning

confidence: 99%

Quantum corrections to conductivity of disordered electrons due to inelastic scattering off magnetic impurities

Burmistrov

Repin

2018

We study the quantum corrections to the conductivity of the two-dimensional disordered interacting electron system in the diffusive regime due to inelastic scattering off rare magnetic impurities. We focus on the case of very different g-factors for electrons and magnetic impurities. Within the Born approximation for the inelastic scattering off magnetic impurities we find additional temperaturedependent corrections to the conductivity of the Altshuler-Aronov type. Our results demonstrate that the low temperature transport in interacting disordered electron systems with rare magnetic impurities is more interesting than it was commonly believed on the basis of treatment of magnetic impurity spins as classical ones.