Theoretical Solid State Physics

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Fermi surface reconstruction using ancilla spins - NRG + DMFT study

The transition from a conventional metal with a large Fermi surface to a metal with a small Fermi surface, violating Luttingers theorem, is currently of major interest. Such Fermi surface reconstructions can be found in various materials, for example heavy-fermion compounds [1] and cuprate high-T_c superconductors [2]. In a recent paper [3], Zhang and Sachdev propose a Hubbard model with ancilla spins for such a transition, which they solve with a static mean-field Ansatz. However, the proposed model may also be treated using the Dynamical Mean-Field Theory (DMFT) together with the Numerical Renormalization Group (NRG) to obtain a picture going beyond the static mean-field description.
The project aims at comparing the findings of [3] with the DMFT solution to the model, using code provided by our group.


[1] S. Paschen et al.,
[2] S. Badoux et al.,
[3] Y. Zhang and S. Sachdev,