Athermal domain-wall creep near a ferroelectric quantum critical point

Ferroelectric domain walls that separate regions with distinct electric-polarization directions 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. Non-linear 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 (QCP). 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 QCP [1].
[1] F. Kagawa et al., Nat. Commun. 7:10675 (2016).