Band structure of pnictides: effects of crystal symmetry and pressure*

Even after ten years of intensive studies of iron-based superconductors these remarkable materials still remain enigmatic due to their large structural variety and a complex interplay of magnetism and superconductivity. Recently discovered AeAFe₄As₄ (1144) pnictides revealed new exciting phenomena, such as the spin-vortex magnetism [1] and pressure-induced half-collapse transitions [2], that originate from the special crystal symmetry.

In this talk, the effects of pressure and structural symmetry on the electronic properties of these 1144 materials are addressed from first principles. We focus here on the general trends in this pnictide family and compare them with the 122-type pnictides. Our simulations [3] show the importance of spin-vortex fluctuations and a high tunability of magnetism and superconductivity in these systems.

This work was done in collaboration with Peter Orth (Ames Laboratory), Seok-Woo Lee (University of Connecticut), Rafael Fernandes (University of Minnesota) and Cristian Batista (University of Tennessee).

References
1. W.R. Meier et al., Nat. Quant. Mat. 3, 5 (2018).
2. U.S. Kaluarachchi et al., PRB 96, 140501(R) (2017).
3. V. Borisov, P. C. Canfield, R. Valenti, PRB 98, 064104 (2018). Editors' Suggestion.