Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 3: Superconductivity: Properties and Electronic Structure I

TT 3.13: Vortrag

Montag, 12. März 2018, 12:45–13:00, H 0110

Single-gap superconductivity in Nb-doped SrTiO₃ and superconducting dome probed by microwave spectroscopy — Markus Thiemann¹, Manfred H. Beutel¹, Martin Dressel¹, Nicholas R. Lee-Hone², David M. Broun^{2, 3}, Evangelos Fillis-Tsirakis⁴, Hans Boschker⁴, Jochen Mannhart⁴, and •Marc Scheffler¹ — ¹1. Physikalisches Institut, Universität Stuttgart, Stuttgart, Germany — ²Department of Physics, Simon Fraser University, Burnaby, Canada — ³Canadian Institute for Advance Research, Toronto, Canada — ⁴Max Planck Institute for Solid State Research, Stuttgart, Germany

SrTiO₃ exhibits a superconducting dome (critical temperature T_c up to 0.4 K) upon doping with Nb, which successively fills multiple bands at the Fermi level. Using superconducting microwave stripline resonators at frequencies 2 to 23 GHz and temperatures down to 0.02 K, we probe the low-energy optical response of superconducting SrTiO₃ with charge carrier concentration from 0.3 to 2.2× 10²⁰ cm⁻³ across the superconducting dome. We find single-gap behavior [1] although several electronic bands are superconducting in SrTiO₃, and this presence of a single energy gap 2Δ due to gap homogenization over the Fermi surface is consistent with the amount of defect scattering observed in Nb-doped SrTiO₃. Furthermore, we determine T_c, 2Δ, and the superfluid density throughout the superconducting regime of Nb-doped SrTiO₃, and all three quantities exhibit the characteristic dome shape as a function of Nb concentration.
M. Thiemann et al., arXiv:1703.04716