Defect-Strain Engineering Stabilized Multiferroic Properties in Non-Stoichiometric SrTiO₃ Epitaxial Thin Films and...

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Perovskite oxide films and membranes are crucial for next-generation electronics due to multiferroic properties and low dimensionality.
• Strontium titanate (SrTiO3) exhibits challenges in achieving stable room-temperature ferroelectricity and magnetism, especially in freestanding membranes.

Purpose of the Study:

• To engineer non-stoichiometric strontium titanate (SrTiO3) thin films and freestanding membranes with enhanced ferroelectric and magnetic properties.
• To investigate the effects of Ti deficiency and oxygen vacancies on the multiferroic behavior of SrTiO3.

Main Methods:

• Defect-strain engineering was employed to introduce Ti deficiency/O-vacancy into SrTiO3 thin films.
• Preparation of non-stoichiometric epitaxial SrTiO3 thin films with a Sr/Ti ratio of 0.6/0.4.
• Fabrication of freestanding non-stoichiometric SrTiO3 membranes, preserving compressive strain.

Main Results:

• Non-stoichiometric SrTiO3 thin films (Sr/Ti = 0.6/0.4) showed a stable tetragonal phase with coexistent relaxor ferroelectricity and magnetism.
• Freestanding non-stoichiometric SrTiO3 membranes retained compressive strain and exhibited a polar tetragonal phase with significant ferroelectricity and magnetism.
• The observed properties are attributed to the presence of polar nanoregions induced by defect-strain engineering.

Conclusions:

• Defect-strain engineering is an effective approach to achieve stable ferroelectricity and magnetism in both SrTiO3 thin films and freestanding membranes.
• This method enhances the potential of SrTiO3 materials for multifunctional semiconductor applications.