High-T(c) Superconductivity at the Interface between the CaCuO2 and SrTiO3 Insulating Oxides

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Complex oxide interfaces can exhibit emergent electronic properties not found in bulk materials.
• Superconductivity has been observed at oxide interfaces, but typically with very low critical temperatures (Tc).

Purpose of the Study:

• To investigate the occurrence of high-Tc superconductivity at the interface between insulating CaCuO(2) and SrTiO(3) oxides.
• To understand the structural and electronic requirements for superconductivity at this interface.

Main Methods:

• Fabrication of CaCuO(2)/SrTiO(3) bilayers with specific interface termination (Ca plane of CaCuO(2) to TiO(2) plane of SrTiO(3)).
• Utilized scanning transmission electron microscopy and electron-energy-loss spectroscopy (EELS) at the O K edge to analyze the hole doping profile.

Main Results:

• High-Tc superconductivity was achieved in the CaCuO(2)/SrTiO(3) bilayer system.
• Oxygen incorporation into the Ca plane of CaCuO(2) acts as apical oxygen for Cu, providing necessary holes for superconductivity.
• Superconductivity is spatially confined to approximately 1-2 unit cells of CaCuO(2) adjacent to the SrTiO(3) interface.

Conclusions:

• The CaCuO(2)/SrTiO(3) interface provides a route to high-Tc superconductivity in insulating oxides.
• The findings offer insights into the mechanism of superconductivity in cuprates and can inform the design of multilayered high-Tc cuprate superconductors.