A FUNCTIONAL RENORMALIZATION GROUP STUDY OF STRONGLY CORRELATED ELECTRON SYSTEMS

Speaker: Nahom Yirga, Boston University, Physics Department

When: April 5, 2021 (Mon), 03:30PM to 04:30PM (add to my calendar)

This event is part of the Departmental Seminars.

This work is concerned with the application of functional renormalization group (fRG) to the study of interacting fermionic systems. We consider a decoupled for- mulation of the fRG equations that retains much of the flow of relevant modes in the system. The decoupling is optimized in the frequency and momentum domains for a general multiband system of interacting electrons. This optimized decoupling is then used to derive the flow equations that describe fluctuations in model Hamil- tonians for Cuprate and Pnictide superconductors. Accounting for the frequency modes in the system allows us to explore the impact of coupling phonons to these model Hamiltonians. We construct a full phase diagram of the systems studied as a function of doping, temperature and coupling. Alterations to the diagram due to electron-phonon coupling is derived. The results of the decoupled formulation is in agreement with results in the literature for many of the models considered. Further the fRG captures the sensitivity of susceptibilities of Cuprate Hamiltonians to band structure, the enhanced role of Hunds coupling in Pnictide systems and the impact of phonons in multiband Hamiltonians.