Soft modes in order-disorder ferroelectrics

Liu, ZR Duan, WH Gu, BL Zhang, XW

Zr. Liu et al., Soft modes in order-disorder ferroelectrics, APPL PHYS L, 79(9), 2001, pp. 1333-1335

12

INGLESE

Article

Apllied Physucs/Condensed Matter/Materiales Science

APPLIED PHYSICS LETTERS

0003-6951 → ACNP

79

9

2001

1333 - 1335

ISI

0003-6951(20010827)79:9<1333:SMIOF>2.0.ZU;2-2

We find that the conventional method to calculate the soft-mode frequency o f the pseudospin model is incorrect, and present a valid modified method. I t is demonstrated that the conventional method does not show the soft-mode frequency going to zero at a critical temperature in the presence of random internal fields, while the frequency calculated by our modified method goe s to zero in random fields at a critical temperature. For the field-induced phase transition relaxor ferroelectrics, the soft-mode frequency decreases to zero at the first-order phase transition temperature though the symmetr y has been destroyed at high temperatures under an external field. (C) 2001 American Institute of Physics.