Zero-Bias Conductance Peaks Effectively Tuned by Gating-Controlled Rashba Spin-Orbit Coupling

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Phenomena

Background:

• Zero-bias conductance peaks (ZBCBs) are crucial indicators of physical phenomena in electronic systems.
• The LaAlO_{3}/SrTiO_{3} interface hosts a two-dimensional electron system (2DES) with gate-tunable Rashba spin-orbit coupling (SOC).

Purpose of the Study:

• To investigate the origin and gate dependence of ZBCPs in hybrid LaAlO_{3}/SrTiO_{3}/Nb junctions.
• To explore the influence of Rashba SOC on superconductivity and Andreev reflection in these hybrid structures.

Main Methods:

• Fabrication of hybrid junctions using LaAlO_{3}/SrTiO_{3} heterostructures and Nb.
• Experimental measurement of ZBCPs and their dependence on gate voltage.
• Theoretical modeling of electron transport, Andreev reflection, and SOC effects.

Main Results:

• Observed pronounced ZBCPs in the hybrid junctions, showing a domelike dependence on gate voltage.
• Correlated the gate dependence of ZBCPs with the nonmonotonic gate modulation of Rashba SOC in the 2DES.
• Attributed ZBCPs to reflectionless tunneling via phase-coherent multiple Andreev reflection.
• Theoretically demonstrated that Rashba SOC enhances Andreev conductance in 2DES-barrier-superconductor junctions.

Conclusions:

• The study reveals a significant interplay between electron spin and superconductivity, evidenced by ZBCPs.
• Gate-tunable Rashba SOC in 2DES provides a novel pathway for controlling superconducting properties.
• Findings have implications for superconducting spintronics and the pursuit of topological superconductivity.