Revealing Hidden Orbital Pseudospin Texture with Time-Reversal Dichroism in Photoelectron Angular Distributions

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• 2H-WSe2 is a layered transition metal dichalcogenide with potential applications in spintronics.
• Understanding the interplay of spin and orbital degrees of freedom is crucial for designing novel electronic devices.
• Existing techniques like spin-resolved ARPES provide insights into spin textures but not directly into orbital pseudospin textures.

Purpose of the Study:

• To introduce and validate a new observable, time-reversal dichroism in photoelectron angular distributions (TRDAD).
• To demonstrate that TRDAD can unveil the hidden orbital pseudospin texture in bulk 2H-WSe2.
• To establish TRDAD as a complementary probe to spin-resolved ARPES for multiorbital systems.

Main Methods:

• Angle-resolved photoemission spectroscopy (ARPES) was performed on bulk 2H-WSe2.
• A novel observable, TRDAD, was defined to quantify photoemission intensity modulation under time-reversal operations.
• Experimental results were compared with tight-binding models and one-step photoemission calculations.

Main Results:

• TRDAD successfully quantifies the modulation of photoemission intensity upon effective time-reversal.
• The hidden orbital pseudospin texture of 2H-WSe2 leaves a distinct imprint on TRDAD.
• Multiple orbital interference effects in photoemission are responsible for this observation.
• Experimental findings show quantitative agreement with theoretical calculations.

Conclusions:

• TRDAD is a powerful new tool for probing orbital pseudospin textures.
• This technique complements spin-resolved ARPES by providing direct access to orbital pseudospin information.
• The findings advance our understanding of spin-orbital entanglement in multiorbital materials.