Ab initio prediction of pressure-induced structural phase transition of superconducting FeSe.
External pressure driven phase transitions of FeSe are predicted using ab initio calculations. The calculations reveal that α-FeSe makes transitions to NiAs-type, MnP-type, and CsCl-type FeSe. Transitions from NiAs-type to MnP-type and CsCl-type FeSe are also predicted. MnP-type FeSe is also found to be able to transform to CsCl-type FeSe, which is easier from α-FeSe than the transition to MnP-type FeSe, but comparable to the transition from NiAs-type FeSe. The calculated electronic structures show that all phases of FeSe are metallic, but the ionic interaction between Fe-Se bonds becomes stronger and the covalent interaction becomes weaker when the structural phase transition occurs from α-FeSe to the other phases of FeSe. The experimentally observed decrease in T(c) of superconducting α-FeSe at high pressure may be due to a structural/magnetic instability, which exists at high pressure. The results suggest an increase of the T(c) of α-FeSe if such phase transitions are frustrated by suitable methods.
Department of Physics, Quaid-i-Azam University, Islamabad 45320, Pakistan.
Gul
G
Rahman
In Gee
IG
Kim
Arthur J
AJ
Freeman
D003198:Computer Simulation; D004553:Electric Conductivity; D004583:Electrons; D058085:Iron Compounds / Q000737:chemistry*; D008956:Models, Chemical; D044367:Phase Transition; D011312:Pressure; D012643:Selenium / Q000737:chemistry*; D013816:Thermodynamics
D058085:Iron Compounds; D012643:Selenium