Spin-phonon coupling effects in transition-metal perovskites: A DFT+U and hybrid-functional study

Jiawang Hong*, Alessandro Stroppa, Jorge Añiguez, Silvia Picozzi, David Vanderbilt

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

148 Citations (Scopus)

Abstract

Spin-phonon coupling effects, as reflected in phonon frequency shifts between ferromagnetic (FM) and G-type antiferromagnetic (AFM) configurations in cubic CaMnO 3, SrMnO 3, BaMnO 3, LaCrO 3, LaFeO 3, and La 2(CrFe)O 6, are investigated using density-functional methods. The calculations are carried out both with a hybrid-functional Heyd-Scuseria-Ernzerhof (HSE) approach and with a DFT+ U approach using a U that has been fitted to HSE calculations. The phonon frequency shifts obtained in going from the FM to the AFM spin configuration agree well with those computed directly from the more accurate HSE approach, but are obtained with much less computational effort. We find that in the AMnO 3 materials class with A= Ca, Sr, and Ba, this frequency shift decreases as the A cation radius increases for the Γ phonons, while it increases for R-point phonons. In LaMO 3 with M= Cr, Fe, and Cr/Fe, the phonon frequencies at Γ decrease as the spin order changes from AFM to FM for LaCrO 3 and LaFeO 3, but they increase for the double perovskite La 2(CrFe)O 6. We discuss these results and the prospects for bulk and superlattice forms of these materials to be useful as multiferroics.

Original languageEnglish
Article number054417
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume85
Issue number5
DOIs
Publication statusPublished - 15 Feb 2012
Externally publishedYes

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