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Ferroelectric Ordering in the Relaxor Pb(Mg1/3Nb2/3)O3 as Evidenced by Low-Temperature Phonon Anomalies

S. Wakimoto·C. Stock·R. J. Birgeneau·Z. -G. Ye·W. Chen·W. J. L. Buyers·P. M. Gehring·G. Shirane
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Abstract

Neutron scattering measurements of the lowest-energy TO phonons in the relaxor Pb(Mg1/3Nb2/3)O3 (PMN) are reported for 10<=T<=750 K. The soft mode, which is overdamped by the polar nanoregions below the Burns temperature T_d = 620 K, surprisingly recovers below 220 K. The square of the soft mode energy hw0^2 increases linearly with decreasing temperature, and is consistent with the behavior of a ferroelectric soft mode. At 10 K, hw0 reaches 11 meV, the same value observed in ferroelectric Pb(Zn1/3Nb2/3)O3 at low-T. An unusual broadening of the TA phonon starts at T_d and disappears at 220 K, coincident with the recovery of the TO mode. These dynamics suggest that a well-developed ferroelectric state is established below 220 K.

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S. Wakimoto, C. Stock, R. J. Birgeneau, Z. -G. Ye, W. Chen, W. J. L. Buyers, P. M. Gehring, G. Shirane. 2002-03-01. Ferroelectric Ordering in the Relaxor Pb(Mg1/3Nb2/3)O3 as Evidenced by Low-Temperature Phonon Anomalies. https://doi.org/10.1103/physrevb.65.172105

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