Quasi-particle spectrum in trilayer graphene: Role of onsite coulomb interaction and interlayer coupling

• Analysis of the quasi-particle spectrum in trilayer graphene.
• The expressions are obtained using Green׳s function equations of motion approach.
• Enhancement in Coulomb interaction energy generates a gap at Fermi level.
• Enhancement in t⊥, Introduce a finite DOS at Fermi point in ABC-stacking.

Stacking dependent quasi-particle spectrum and density of states (DOS) in trilayer (ABC-, ABA- and AAA-stacked) graphene are analyzed using mean-field Green׳s function equations of motion method. Interlayer coupling (t1) is found to be responsible for the splitting of quasi-particle peaks in each stacking order. Coulomb interaction suppresses the trilayer splitting and generates a finite gap at Fermi level in ABC- while a tiny gap in ABA-stacked trilayer graphene. Influence of t⊥ is prominent for AAA-stacking as compared to ABC- and ABA-stacking orders. The theoretically obtained quasi-particle energies and DOS has been viewed in terms of recent angle resolved photoemission spectroscopic (ARPES) and scanning tunneling microscopic (STM) data available on these systems.

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