2012/11/30 by Xiao Lin, Zengwei Zhu, Benoit Fauque +1 · 1 citation
Physics and Astronomy · #cond-mat.supr-con #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1103/physrevx.3.021002
published as Phys. Rev. X 3, 021002 (2013) · Final version
arxiv created 2013/04/15 · arxiv updated 2013/04/16
The origin of superconductivity in bulk SrTiO3 is a mystery, since the non-monotonous variation of the critical transition with carrier concentration defies the expectations of the crudest version of the BCS theory. Here, employing the Nernst effect, an extremely sensitive probe of tiny bulk Fermi surfaces, we show that down to concentrations as low as 5.5 × 1017cm-3, the system has both a sharp Fermi surface and a superconducting ground state. The most dilute superconductor currently known has therefore a metallic normal state with a Fermi energy as little as 1.1 meV on top of a band gap as large as 3 eV. Occurrence of a superconducting instability in an extremely small, single-component and barely anisotropic Fermi surface implies strong constraints for the identification of the pairing mechanism.