Local switching of two-dimensional superconductivity using the ferroelectric field effect

Area of Science:

• Condensed Matter Physics
• Materials Science
• Oxide Electronics

Background:

• Correlated oxides exhibit complex physical properties like superconductivity and colossal magnetoresistance.
• Tuning doping levels in these materials is crucial for understanding their phase diagrams.
• Electric field control offers a flexible method to modulate carrier concentration, similar to semiconductor field-effect transistors.

Purpose of the Study:

• To investigate the ferroelectric field effect in a model oxide system.
• To demonstrate the ability to tune superconducting properties using electric fields.
• To explore the potential for creating novel electronic devices based on controlled superconductivity.

Main Methods:

• Fabrication of high-quality heterostructures using Nb-doped SrTiO3 (superconducting channel) and Pb(Zr,Ti)O3 (gate oxide).
• Utilizing atomic force microscopy to locally reverse ferroelectric polarization.
• Measuring resistivity and carrier modulations to observe changes in superconducting critical temperature.

Main Results:

• Large modulations in resistivity and carrier concentration were induced by the ferroelectric field effect.
• A clear shift in the superconducting critical temperature was observed.
• Field-induced switching between the normal and superconducting states was achieved.

Conclusions:

• The ferroelectric field effect is a viable method for controlling superconductivity in oxide heterostructures.
• This approach enables the local definition of superconducting and normal regions within the same material, creating 'perfect' electronic interfaces.
• Potential applications include the design of one-dimensional superconducting wires, Josephson junctions, and superconducting quantum interference devices (SQUIDs).