2017/03/31 by Clément Collignon, Benoit Fauqué, Benoît Fauqué +7
Materials Science · Physics and Astronomy · #Condensed matter physics #Cuprate #Doping #Electronic and Structural Properties of Oxides #Magnetic and transport properties of perovskites and related materials #Materials science #Penetration depth #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #Strontium titanate #Superconductivity #Superfluidity #Thin film #cond-mat.mtrl-sci #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.96.224506
published as Phys. Rev. B 96, 224506 (2017) · 9 pages including 6 figures
openalex created_date 2017/03/16 · arxiv created 2017/12/14 · openalex publication_date 2017/12/14 · arxiv updated 2017/12/15 · openalex updated_date 2026/08/05
We present a study of the lower critical field, Hc1, of SrTi_1\ensuremath-xNbxO3 as a function of carrier concentration with the aim of quantifying the superfluid density. At low carrier concentration (i.e., the underdoped side), superfluid density and the carrier concentration in the normal state are equal within experimental margin. A significant deviation between the two numbers starts at optimal doping and gradually increases with doping. The inverse of the penetration depth and the critical temperature follow parallel evolutions as in the case of cuprate superconductors. In the overdoped regime, the zero-temperature superfluid density becomes much lower than the normal-state carrier density before vanishing all together. We show that the density mismatch and the clean-to-dirty crossover are concomitant. Our results imply that the discrepancy between normal and superconducting densities is expected whenever the superconducting gap becomes small enough to put the system in the dirty limit. A quantitative test of the dirty BCS theory is not straightforward, due to the multiplicity of the bands in superconducting strontium titanate.