Bias-Free Access to Orbital Angular Momentum in Two-Dimensional Quantum Materials

Area of Science:

• Condensed Matter Physics
• Quantum Materials Science

Background:

• Topological band inversion is key to identifying quantum spin Hall insulators (QSHIs).
• Bulk Berry curvature, linked to orbital angular momentum (OAM), is a fundamental property of these materials.
• Circular dichroism in angle-resolved photoemission spectroscopy (CD-ARPES) can probe OAM, but is hindered by interfering signals.

Purpose of the Study:

• To develop an experimental strategy for isolating the initial state OAM signal in CD-ARPES.
• To overcome interference artifacts from final state photoelectron emission channels.
• To establish CD-ARPES as a scalable tool for classifying topological quantum materials.

Main Methods:

• A full-experimental strategy was devised to isolate clean OAM from CD-ARPES data.
• The strategy was benchmarked using the atomic monolayer system, indenene.
• Analysis focused on identifying topological band inversion and Berry curvature.

Main Results:

• The proposed strategy successfully isolates the OAM signature from CD-ARPES.
• Indenene was confirmed to possess distinct quantum spin Hall insulator characteristics.
• The method demonstrates the potential of CD-ARPES as a bulk probe for topological materials.

Conclusions:

• CD-ARPES, with the developed strategy, can reliably measure OAM and probe Berry curvature.
• This advancement enables the experimental classification of 2D quantum materials with time-reversal symmetry.
• The findings pave the way for broader applications of CD-ARPES in topological material discovery.