First-principles study of CaFe2As2 under pressure

Michael Widom and Khandker Quader
Phys. Rev. B 88, 045117 – Published 15 July 2013

Abstract

We perform first-principles calculations on CaFe2As2 under hydrostatic pressure. Our total-energy calculations show that though the striped antiferromagnetic (AFM) orthorhombic (OR) phase is favored at P=0, a nonmagnetic collapsed tetragonal (cT) phase with diminished c parameter is favored for P>0.36 GPa, in agreement with experiments. Rather than a mechanical instability, this is an enthalpically driven transition from the higher volume OR phase to the lower volume cT phase. A simple thermodynamic model provides an interpretation of the finite-temperature phase boundaries of the cT phase. Calculations of electronic density of states reveal pseudogaps in both OR and cT phases. Band-structure analysis provides insight into the origin of the pseudogaps while revealing the location and nature of hybridized Fe-d and As-p bonding orbitals.

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  • Received 21 May 2013

DOI:https://doi.org/10.1103/PhysRevB.88.045117

©2013 American Physical Society

Authors & Affiliations

Michael Widom

  • Department of Physics, Carnegie-Mellon University, Pittsburgh, Pennsylvania 15213, USA

Khandker Quader

  • Department of Physics, Kent State University, Kent, Ohio 44242, USA

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Issue

Vol. 88, Iss. 4 — 15 July 2013

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