Orbital angular momentum analysis for giant spin splitting in solids and nanostructures

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• Giant spin splitting (GSS) is observed in various materials, exceeding the standard Rashba effect.
• Orbital angular momentum (OAM) is unquenched in some GSS materials, linked to interorbital hopping.
• The relationship between unquenched OAM and interorbital hopping as a control for GSS is under-explored.

Purpose of the Study:

• To analyze orbital angular momentum (OAM) in giant spin splitting (GSS) materials using the interorbital-hopping mechanism.
• To investigate the relationship between interatomic hopping, broken mirror symmetry, and resultant spin splitting.
• To demonstrate systematic control of GSS via OAM manipulation.

Main Methods:

• First-principles calculations to analyze OAM in GSS materials.
• Investigating the interorbital-hopping mechanism driven by broken mirror symmetry.
• Exploring control of OAM and GSS through external stimuli like pressure and fields.

Main Results:

• Interatomic hopping between different-parity orbitals generates k-dependent OAM.
• This leads to valley-dependent GSS in WSe2 monolayer, Rashba-type GSS in Au (111), and Dresselhaus-type GSS in HgTe.
• Systematic control of OAM and GSS is demonstrated using pressure, external fields, and substrates.

Conclusions:

• Interorbital hopping is a key mechanism for generating k-dependent OAM and GSS.
• OAM can be systematically controlled, offering a pathway for designing GSS materials.
• The findings provide a simplified framework for understanding and engineering GSS phenomena.