Athermal domain-wall creep near a ferroelectric quantum critical point

Abstract

Ferroelectric domain walls are typically stationary because of the presence of a pinning potential. Nevertheless, thermally activated, irreversible creep motion can occur under a moderate electric field, thereby underlying rewritable and non-volatile memory applications. Conversely, as the temperature decreases, the occurrence of creep motion becomes less likely and eventually impossible under realistic electric-field magnitudes. Here we show that such frozen ferroelectric domain walls recover their mobility under the influence of quantum fluctuations. Nonlinear permittivity and polarization-retention measurements of an organic charge-transfer complex reveal that ferroelectric domain-wall creep occurs via an athermal process when the system is tuned close to a pressure-driven ferroelectric quantum critical point. Despite the heavy masses of material building blocks such as molecules, the estimated effective mass of the domain wall is comparable to the proton mass, indicating the realization of a ferroelectric domain wall with a quantum-particle nature near the quantum critical point.

Quantum Phenomena Emerging Near a Ferroelectric Critical Point in a Donor–Acceptor Organic Charge-Transfer Complex

“…In this article, we highlight our recent progress in the study of quantum phenomena associated with the ferroelectric QCP, with a particular focus on the organic charge-transfer complex TTF-2,5-QBr 2 I 2 [20,21]. In contrast to DMTTF-2,6-QBr 4−n Cl n , which is located near an antiferroelectric QCP [22], TTF-2,5-QBr 2 I 2 exhibits a ferroelectric QCP under a moderate pressure of 0.25-0.26 GPa, which thus facilitates experimental characterizations of order-parameter-related quantities such as spontaneous electric polarization and permittivity with the pressure as a control parameter for the quantum phase transition.…”

Hydrodynamics of domain walls in ferroelectrics and multiferroics: Impact on memory devices

“…In the present work we extend this analysis to relate to quantitative measurements of domain wall velocities [21][22][23][24][25][26][27] and effective masses for domain walls.…”

“…1 nms -1 . [24][25][26][27][28][29][30] The ferroelastic domain wall viscosity is very large compared with normal liquids, and comparable to that in martensitic metals; a rough estimate by Scott 3 is 10 6 poise for domain wall viscosity and by Salje and …”

“…one proton mass m p . 27 The basic idea is that relatively low-viscosity media produce folds, whereas higher viscosity media produce skyrmions and vertex structures. [28][29][30][31] The vortex structures (and skyrmions [32][33][34][35] ) are analogous to high viscosity aa-aa lava, just as the smooth folds are analogous to those in lower viscosity ropy pahoehoe.…”

Quantum critical points in ferroelectric relaxors: Stuffed tungsten bronze K3Li2Ta5OSmith1, Gardner2, Morrison3 et al. 2018Phys. Rev. Materials3020View full textAdd to dashboardCite

“…However, as the dynamical exponent is 1 for displacive FE rather than 3 for itinerant ferromagnets, the understanding and modeling of their properties are likely to be more complex, since real systems can exceed the upper and lower critical dimensionality [1]. For a QCP to occur, the transition should be driven by quantum fluctuations rather than classical fluctuations, and such quantum fluctuations tend to dominate in a region just above 0 K. Interest in ferroelectric quantum critical points has grown rapidly in the past several years, with emphasis upon perovskites [1,2] and several other materials, including hexaferrites [3][4][5][6] and organic or molecular crystals [7][8][9][10]. However, the QCPs studied thus far do not include many crystal families, and with one recent exception [11], no glassy relaxors.…”