Variationally optimized orbital approach to trions in two-dimensional materials.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• Trions, quasiparticles composed of two electrons and a hole or vice versa, are crucial in understanding optical properties of low-dimensional materials.
• Accurate theoretical calculations of trion properties are essential for predicting and interpreting experimental observations.

Purpose of the Study:

• To develop and apply an efficient variational method for calculating trion energy levels and wavefunctions in two-dimensional systems.
• To investigate the binding properties of ground-state and excited-state trions in 2D hydrogen-like systems and monolayer transition metal dichalcogenides (TMDCs).

Main Methods:

• Utilizing a variational method with trial wavefunctions constructed from 2D slater-type orbitals.
• Applying the method to a 2D hydrogen-like system across various mass ratios and screening lengths.
• Extending the calculations to monolayer TMDCs, incorporating the electron-hole exchange (EHX) interaction.

Main Results:

• The ground-state trion is found to be bound across all investigated parameters in the 2D hydrogen-like system.
• An excited-state trion can be bound for large electron-hole mass ratios or long screening lengths.
• Calculated binding energies for ground-state trions show good agreement with more complex methods.
• The EHX interaction significantly impacts trion binding energies and the stability of excited-state trions in TMDCs.

Conclusions:

• The developed variational method provides an accurate and efficient approach for studying trions in 2D systems.
• The findings highlight the conditions under which excited-state trions can be stable, particularly in TMDCs.
• This research contributes to a deeper understanding of quasiparticle physics in low-dimensional materials.