Variation in superconducting transition temperature due to tetragonal domains in two-dimensionally doped SrTiO3

Hilary Noad, Eric M. Spanton, Katja C. Nowack, Hisashi Inoue, Minu Kim, Tyler A. Merz, Christopher Bell, Yasuyuki Hikita, Ruqing Xu, Wenjun Liu, Arturas Vailionis, Harold Y. Hwang (+1 others)
2016 Physical review B  
Strontium titanate is a low-temperature, non-Bardeen-Cooper-Schrieffer superconductor that superconducts to carrier concentrations lower than in any other system and exhibits avoided ferroelectricity at low temperatures. Neither the mechanism of superconductivity in strontium titanate nor the importance of the structure and dielectric properties for the superconductivity are well understood. We studied the effects of twin structure on superconductivity in a 5.5-nm-thick layer of niobium-doped
more » ... TiO_3 embedded in undoped SrTiO_3. We used a scanning superconducting quantum interference device susceptometer to image the local diamagnetic response of the sample as a function of temperature. We observed regions that exhibited a superconducting transition temperature T_c ≳ 10 which the sample was fully superconducting. The pattern of these regions varied spatially in a manner characteristic of structural twin domains. Our results emphasize that the anisotropic dielectric properties of SrTiO_3 are important for its superconductivity, and need to be considered in any theory of the mechanism of the superconductivity.
doi:10.1103/physrevb.94.174516 fatcat:k3hkroecofawdcb636x4y7vc6q