Regensburg 2022 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 3: Superconductivity: Properties and Electronic Structure
TT 3.6: Vortrag
Montag, 5. September 2022, 10:45–11:00, H23
Cascade of collapsed phases in SrNi2P2 and CaKFe2As2 under various strain conditions — •Adrian Valadkhani1, Shuyang Xiao2, Igor Mazin3, Seok-Woo Lee2, Paul Canfield4, and Roser Valenti1 — 1Goethe University, Frankfurt am Main, Germany — 2University of Connecticut, Connecticut, United States — 3George Mason University, Fairfax, USA — 4Iowa State University, Ames, United States
Most of crystalline solids have a maximum recoverable strain of less than 1%. Further strain will cause plastic deformation or fractures. In the current work we present SrNi2P2, whose maximum recoverable compressive strain is ∼ 14% and tensile is ∼ 6% . These widespread values of strain are realizable due to a double lattice collapse-expansion mechanism. The ab initio density functional theory calculations are in very good agreement with the experiment[1,2]. Instead of the usual uncollapsed to collapsed tetragonal transition for the generic tetragonal 122s, a second transition to an orthorhombic superstructure is observed. By a detailed investigation of the electronic and geometric structures for various strains, and substitutions of the Sr, Ni, (and /) or P from first principles, we are able to give a deeper insight in the theory description of this doubly lattice collapse-expansion mechanism. Within this framework we will also discuss structural phases in CaKFe2As2 under varios strain conditions.
This work is support by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) for funding through TRR 288.
[1] Nano Lett. 2021, 21, 19, 7913
[2] Phys. Rev. B 56, 13796 (1997)