Ferroelectric Rashba topological phase in noncentrosymmetric CsSiBi

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Chemistry

Background:

• Composite quantum compounds (CQCs) enable exploration of coupled physical phenomena.
• Giant Rashba effect, ferroelectric switching, and non-trivial band topology are key material characteristics.
• These properties offer novel functionalities and fundamental physics insights.

Purpose of the Study:

• Investigate CsSiBi and CsPbSb as potential CQCs.
• Analyze their stability and properties using first-principles calculations.
• Identify materials with combined topological, Rashba, and ferroelectric characteristics.

Main Methods:

• First-principles calculations using VASP and WIEN2k.
• Symmetry analysis for electronic band structure.
• Evaluation of chemical, mechanical, dynamical, and thermal stability.

Main Results:

• CsSiBi identified as an intrinsic CQC with topological insulating phase, Rashba spin-splitting, and ferroelectric switching.
• CsPbSb shows a very large Rashba effect.
• Calculated giant isotropic Rashba effect (αR ≈ 2.46 eV Å) in CsSiBi.
• Ferroelectricity validated by spin-texture reversal and double well energy profile in CsSiBi.

Conclusions:

• CsSiBi is a promising multifunctional material for spintronics and nanoelectronics.
• The study validates the reliability of full-potential codes for complex materials.
• This work opens avenues for designing next-generation multifunctional materials.