Microscopic origin of pressure-induced phase transitions in the iron pnictide superconductors A Fe2 As2: An ab initio molecular dynamics study

Yu Zhong Zhang, Hem C. Kandpal, Ingo Opahle, Harald Olaf Jeschke, Roser Valentí

Research output: Contribution to journalArticle

60 Citations (Scopus)

Abstract

Using ab initio molecular dynamics we investigate the electronic and lattice structure of A Fe2 As2 (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 CaFe2 As2 and its absence in BaFe2 As2. 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.

Original languageEnglish
Article number094530
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume80
Issue number9
DOIs
Publication statusPublished - Sep 30 2009
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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