Microscopic origin of pressure-induced phase transitions in the iron pnictide superconductors AFe2As2: An ab initio molecular dynamics study
Yu-Zhong Zhang, Hem C. Kandpal, Ingo Opahle, Harald O. Jeschke, Roser Valentí
DOI 10.1103/PhysRevB.80.094530 · Physical Review B
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Abstract
Using ab initio molecular dynamics we investigate the electronic and lattice structure of AFe2As2 (A=Ca,Sr,Ba) under pressure. We find that the structural phase transition (orthorhombic to tetragonal symmetry) is always accompanied by a magnetic phase transition in all the compounds while the nature of the transitions is different for the three systems. Our calculations explain the origin of the existence of a collapsed tetragonal phase in CaFe2As2 and its absence in BaFe2As2. We argue that changes in the Fermi-surface nesting features dominate the phase transitions under pressure rather than spin frustration or a Kondo scenario. The consequences for superconductivity are discussed.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| LaFeAsO Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 21 | 12 GPa | unknown |
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