Electron Accumulation and Emergent Magnetism in LaMnO_{3}/SrTiO_{3} Heterostructures

Area of Science:

• Condensed Matter Physics
• Materials Science
• Surface Science

Background:

• Emergent phenomena at oxide interfaces are crucial for advanced electronics and spintronics.
• Polar-mismatched heterostructures like LaMnO3/SrTiO3 exhibit unique interfacial electronic properties.

Purpose of the Study:

• To determine critical thicknesses for electron reconstruction and ferromagnetism in LaMnO3/SrTiO3 (001) heterostructures.
• To understand the relationship between electron accumulation and ferromagnetism at the interface.
• To investigate methods for controlling these emergent phenomena through doping.

Main Methods:

• Element-specific x-ray absorption spectroscopy and dichroism.
• First-principles calculations.
• Synthesis of polar-mismatched LaMnO3/SrTiO3 heterostructures with varying LaMnO3 thicknesses.

Main Results:

• Electron accumulation observed as thin as 2 unit cells (UC) in LaMnO3.
• Ferromagnetism emerged at a critical thickness of 5 UC in LaMnO3.
• Electron overaccumulation was identified as a factor inhibiting ferromagnetism below 5 UC.
• Doping LaMnO3 allowed ferromagnetism in films as thin as 3 UC by neutralizing excessive electrons.

Conclusions:

• The critical thickness for ferromagnetism is distinct from that for electron accumulation in these heterostructures.
• Controlling interfacial electron density via doping is a viable strategy to tailor emergent magnetic properties.
• This work advances the synthesis and manipulation of oxide heterostructures for next-generation electronic and spintronic devices.