First-principles-based simulations of relaxor ferroelectrics

S. TINTE ; B. P. BURTON; E. COCKAYNE; U. V. WAGHMARE

PHYSICAL REVIEW LETTERS

AMERICAN PHYSICAL SOCIETY

Lugar: New York; Año: 2006 vol. 97 p. 137601 - 137604

0031-9007

Molecular dynamics simulations of first-principles-based effective Hamiltonians for Pb(Sc1/2 Nb1/2)O3 under hydrostatic pressure and for Pb(Mg1/3 Nb2/3)O3 at ambient pressure show clear evidence of a relaxor state in both systems. The Burns temperature is identified as the temperature below which dynamic nanoscale polar clusters form, pinned to regions of quenched chemical short-range order. The effect of pressure in Pb(Sc1/2 Nb1/2)O3 demonstrates that the stability of the relaxor state depends on a delicate balance between the energetics that stabilize normal ferroelectricity and the average strength of random local fields which promote the relaxor state.