Haohao Yang | Searcharxiv

arXiv2019

Superconductivity above 28 K in single unit cell FeSe films interfaced with GaO$_{2-δ}$ layer on NdGaO$_{3}$(110)

We prepared single unit cell FeSe films on GaO$_{2-δ}$ terminated perovskite NdGaO$_{3}$(110) substrates and performed ex situ transport and scanning transmission electron microscopy measurements on the FeTe protected films. Our experimental measurements showed that the single unit cell FeSe films interfaced with GaO$_{2-δ}$ layer are electron doped via interface charge transfer. Most importantly, this type of heterostructure can host interface enhanced superconductivity with an onset temperature of about 28 K, which is much higher than the value of 8 K in bulk FeSe. Our work indicates that FeSe/GaO$_{2-δ}$can be a comparative platform with the FeSe/TiO$_{2-δ}$ family for understanding the mechanism of interface enhanced high temperature superconductivity.

cond-mat.supr-con↗

arXiv2018

Observation of tunneling gap in epitaxial ultrathin films of pyrite-type copper disulfide

We report scanning tunneling microscopy investigation on epitaxial ultrathin films of pyrite-type copper disulfide. Layer by layer growth of CuS2 films with a preferential orientation of (111) on SrTiO3(001) and Bi2Sr2CaCu2O8+δ substrates is achieved by molecular beam epitaxy growth. For ultrathin films on both kinds of substrates, we observed symmetric tunneling gap around Fermi level that persists up to ~ 15 K. The tunneling gap degrades with either increasing temperature or increasing thickness, suggesting new matter states at the extreme two dimensional limit.

cond-mat.supr-con↗