Anomalous Rashba spin-orbit interaction in electrically controlled topological insulator based on InN/GaN quantum...

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• Topological phase transitions are crucial for novel electronic properties.
• Rashba spin-orbit interaction in low-dimensional systems offers control over electron spin.
• Indium Nitride/Gallium Nitride (InN/GaN) quantum wells are promising for spintronic applications.

Purpose of the Study:

• To theoretically investigate the topological phase transition in electrically biased InN/GaN quantum wells.
• To analyze the Rashba spin-orbit interaction and its behavior under an external electric field.
• To explore the tunability of edge states and their spin splitting in these structures.

Main Methods:

• Theoretical modeling of quantum wells with specific barrier and well widths.
• Application of an external electric field perpendicular to the quantum well plane.
• Derivation of effective Rashba Hamiltonians and analysis of subband spin splitting.
• Investigation of Hall bar geometry to study edge states.

Main Results:

• The system can be tuned through a topological phase transition by an external electric field.
• An anomalous Rashba effect is observed, where spin splitting decreases with increasing electric field.
• Significant spin splitting of edge states in the 2D band gap can be effectively switched off by the electric field.
• The critical voltage for the topological phase transition depends on the structure's width.

Conclusions:

• Electrically biased InN/GaN quantum wells provide a platform for controlling topological phase transitions and spin properties.
• The anomalous Rashba effect and tunable edge state spin splitting offer potential for spintronic device applications.
• The interplay between quantum well width, electric field, and energy level alignment is critical for manipulating these phenomena.