Local pairing at U impurities in BCS superconductors can enhance Tc

Ivar Martin; Philip Phillips

doi:10.1103/PhysRevB.56.14650

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Local pairing at U impurities in BCS superconductors can enhance Tc

Ivar Martin, Philip Phillips

DOI 10.1103/PhysRevB.56.14650 · Physical Review B

T1

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Abstract

We analyze here the role electrons on Anderson U impurities play in superconductivity in a metal alloy. We find that phonon coupling at impurities counteracts the traditional effects which dominate Tc suppression in the nonmagnetic limit. In some cases, we find that nonmagnetic impurities can enhance Tc. Qualitative agreement is found between the predicted increase and the experimental data for IV-VI degenerate semiconductors doped with Tl or In. In the Kondo limit, a Fermi-liquid analysis reveals that it is the enhancement in the density of states arising from the Kondo resonance that counteracts pair weakening.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
SnTe Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
PbTe Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.2	Pressure not reported	unknown