Cubic Rashba Effect in the Surface Spin Structure of Rare-Earth Ternary Materials

Area of Science:

• Condensed matter physics
• Materials science
• Surface science

Background:

• Spin-orbit interaction and broken inversion symmetry are key for novel spintronic materials.
• Antiferromagnetic materials offer unique spin properties for advanced applications.

Purpose of the Study:

• Investigate spin-polarized carriers on the surface of the antiferromagnet TbRh2Si2.
• Unveil the nature of spin textures and their robustness in magnetic materials.

Main Methods:

• Spin-resolved photoemission spectroscopy on the Si-terminated surface of TbRh2Si2.
• Ab initio one-step theory calculations for electronic structure analysis.
• Development of a two-band k·p model to explain observed spin textures.

Main Results:

• Observed an unusual triple winding of electron spin along surface state energy contours.
• Identified this triple winding as a cubic Rashba effect.
• Demonstrated robust in-plane spin-momentum locking, persisting across magnetic transitions.

Conclusions:

• The cubic Rashba effect governs the observed spin texture in TbRh2Si2.
• Spin-momentum locking is remarkably stable despite varying magnetic order and spin-orbit coupling strengths.
• Findings pave the way for designing materials with highly mobile spin-polarized carriers for spintronics.