TY - JOUR
T1 - Microscopic origin of pressure-induced phase transitions in the iron pnictide superconductors A Fe2 As2
T2 - An ab initio molecular dynamics study
AU - Zhang, Yu Zhong
AU - Kandpal, Hem C.
AU - Opahle, Ingo
AU - Jeschke, Harald Olaf
AU - Valentí, Roser
PY - 2009/9/30
Y1 - 2009/9/30
N2 - 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.
AB - 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.
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U2 - 10.1103/PhysRevB.80.094530
DO - 10.1103/PhysRevB.80.094530
M3 - Article
AN - SCOPUS:70349971155
VL - 80
JO - Physical Review B-Condensed Matter
JF - Physical Review B-Condensed Matter
SN - 1098-0121
IS - 9
M1 - 094530
ER -