University of Minnesota
School of Physics & Astronomy

Condensed Matter Sack Lunch Seminar

Friday, October 14th 2016
Speaker: Ruiqi Xing, University of Minnesota
Subject: Renormalization group analysis of competing instabilities in the four-pocket model for iron-based superconductors

In iron-based superconductors, superconductivity, magnetism and nematic orders are all observed. To understand the phase diagram and the interplay between different orders in iron-based superconductors, we use parquet renormalization group, an unbiased approach, to study the full four-pocket, 3-orbital low-energy model.

Starting from all symmetry-allowed interactions, we derive and analyze the RG flow of the couplings and susceptibilities. We obtain the hierarchy of competing instabilities and obtain, as limiting cases, the behavior, which was previously found in approximate models [A.V. Chubukov, M. Khodas and R.M. Fernandes, arxiv:1602.05503]. For parameters relevant to FeSe, we found that upon lowering the temperature, nematic order is the leading instability, followed by superconductivity, while the magnetic order doesn't appear. We found that the nematic order parameter has three components, and found particular relation between the components, consistent with ARPES experiment[A. Fedorov et al, arxiv:1606.03022].

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