Topological phase transitions via attosecond x-ray absorption spectroscopy

Area of Science:

• Condensed Matter Physics
• Quantum Materials
• Spectroscopy

Background:

• Topological phase transitions are crucial in quantum materials.
• Chern insulators exhibit unique topological properties.
• Probing these transitions requires advanced experimental techniques.

Purpose of the Study:

• To demonstrate capturing topological phase transitions using X-ray absorption spectroscopy.
• To investigate the use of ultrafast laser-driven electron dynamics for probing topological states.
• To connect spectroscopic signatures with the system's Berry curvature.

Main Methods:

• Numerical experiments simulating electron motion under laser excitation.
• Modeling an out-of-equilibrium attosecond spectroscopy scheme.
• Utilizing a circularly polarized infrared pump pulse and an attosecond X-ray probe pulse.

Main Results:

• A laser-induced dichroism-type spectrum clearly indicates a topological phase transition.
• The observed spectral signatures are directly linked to the system's Berry curvature.
• The method successfully identifies the topological phase transition in a Chern insulator model.

Conclusions:

• Attosecond absorption spectroscopy can effectively probe topological phase transitions.
• This technique extends the application of spectroscopy to non-trivial topological phases.
• The study provides a pathway for experimental characterization of topological quantum matter.