Dresden 2017 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 3: Focus: Ferroics with Mesoscopic Order
DF 3.7: Topical Talk
Montag, 20. März 2017, 12:30–13:00, WIL B321
Ferroic glasses: polar nanoregions in relaxor PMN vs. magnetic nanoparticles in a discontinuous multilayer — •Wolfgang Kleemann — Fakultät Physik, Universität Duisburg-Essen, 47048 Duisburg
The term ”ferroic glass” was coined [1] for martensitic, magnetic, and relaxor ferroelectric nanodomain states, which undergo glassy dynamic criticality at T > Tg and non-ergodicity at T < Tg. While these features are also found in ”superspin glass” systems of matrix isolated magnetic nanoparticles as in [Co80Fe20(0.9 nm)/Al2O3(3 nm)] 10 multilayers [2], the mesoscopic ”ferroic glasses” are generally more complex due to the much closer relationship of the nanodomains to the embedding matrix. This is shown for the archetypical relaxor PbMg(1/3) Nb(2/3)O(3) [3], where quenched electric random fields (RF) give rise to creation and growth of polar nanoregions (PNR) on cooling toward Tg with a spectrum of relaxation frequencies skewing from Lacroix-Béné to Cole-Davidson-type. It becomes replaced by relaxation and creep-like domain wall dynamics below Tg, where the PNR percolate and form a ferroelectric microdomain state under the control of the ferroelectric soft lattice mode.
[1] X. B. Ren, Phys. Stat. Sol. B 251, 1982 (2014).
[2] S. Bedanta, O. Petracic and W. Kleemann, Handbook Magn. Mater. 23, 1 (2015).
[3] W. Kleemann and J. Dec, Phys. Rev. B 94, 174203 (2016).