Phonon softenings and the charge density wave instability in R2O2Sb (R=rareearth element)

Heejung Kim, Chang-Jong Kang, Kyoo Kim, J. H. Shim, and B. I. Min
Phys. Rev. B 91, 165130 – Published 24 April 2015

Abstract

To explore the origin of the insulating property of layered system R2O2Sb (R=rareearth element) and to find their distorted superstructures, we have investigated the band structures and phonon dispersions of La2O2Sb and Er2O2Sb based on the ab initio density functional theory. We have found three dominant Fermi surface nesting vectors of q1=0.25a*,q2=0.5a*+0.25b*, and q3=0.25a*+0.25b*. Phonon softening instabilities occur at the same q vectors, which suggests that the lattice instability in Sb layers is driven by the charge density wave instability through the electron-phonon coupling. The linearly superposed mode (ηq3*) of two degenerate normal modes at q3 produces the most stable state with a herringbone-type arrangement of Sb dimers. In the ground state, the distorted Sb square sheet shows the insulating behavior in agreement with existing experiments.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Received 13 January 2015
  • Revised 31 March 2015

DOI:https://doi.org/10.1103/PhysRevB.91.165130

©2015 American Physical Society

Authors & Affiliations

Heejung Kim1, Chang-Jong Kang1, Kyoo Kim1,2, J. H. Shim1,3,*, and B. I. Min1,†

  • 1Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
  • 2c-CCMR, Pohang University of Science and Technology, Pohang 790-784, Korea
  • 3Department of Chemistry and Division of Advanced Nuclear Engineering, Pohang University of Science and Technology, Pohang 790-784, Korea

  • *jhshim@postech.ac.kr
  • bimin@postech.ac.kr

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 91, Iss. 16 — 15 April 2015

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review B

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×