Enhancement of the Rashba Effect in a Conducting SrTiO₃ Surface by MoO₃ Capping

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Asymmetric systems exhibit Rashba spin-orbit interaction, coupling electron spin and momentum.
• This interaction enables nonreciprocal charge transport, crucial for rectifying devices.
• Tuning this interaction unlocks advanced spin-orbitronic functionalities.

Purpose of the Study:

• To investigate nonreciprocal charge transport in a conducting SrTiO3 (001) surface.
• To explore methods for enhancing this transport using surface modifications.
• To demonstrate a tunable platform for spin-orbitronic applications.

Main Methods:

• Created a conductive SrTiO3 (001) surface via Ar+ irradiation to induce oxygen vacancies.
• Probed nonreciprocal signals using angle- and magnetic field-dependent second harmonic voltage measurements with AC current.
• Investigated the effect of irradiation time and a MoO3 capping layer on transport properties.

Main Results:

• Observed robust directional (nonreciprocal) charge transport in irradiated SrTiO3 at low temperatures.
• Found that the nonreciprocal signal magnitude depends on irradiation time, affecting conducting layer depth.
• Significantly enhanced nonreciprocal resistance by adding a MoO3 capping layer.

Conclusions:

• Developed a simple, effective method for tuning the Rashba effect in conductive SrTiO3 surfaces.
• Demonstrated significant enhancement of nonreciprocal transport via a capping layer.
• The methodology is adaptable for various 2D conducting layers in spin-orbitronic applications.