### Session H12: Lattice and Magnetic Properties of Multiferroics

8:00 AM–11:00 AM, Tuesday, March 11, 2008
Morial Convention Center Room: 203

Chair: Andrei Sushkov, University of Maryland

Abstract ID: BAPS.2008.MAR.H12.1

### Abstract: H12.00001 : Infrared phonon dynamics of multiferroic BiFeO$_3$ single crystal

8:00 AM–8:12 AM

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#### Authors:

R.P.S.M. Lobo
(CNRS-ESPCI, Paris, France)

R.L. Moreira
(Depto. Fisica, UFMG, Belo Horizonte, MG, Brazil)

D. Lebeugle
D. Colson
(DSM/DRECAM/SPEC, CEA, Saclay, France)

We discuss the first infrared reflectivity measurement on a BiFeO$_3$ single crystal between 5 K and room temperature. The 9 predicted \textit{ab}-plane $E$ phonon modes are fully and unambiguously determined. The frequencies of the 4 $A_1$ \textit{c}-axis phonons are found. These results settle issues between theory and data on ceramics. Our findings show that the softening of the lowest frequency $E$ mode is responsible for the temperature dependence of the dielectric constant, indicating that the ferroelectric transition in BiFeO$_3$ is soft-mode driven.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2008.MAR.H12.1