Jo J Y, Kim D J, Kim Y S, Choe S-B, Song T K, Yoon J-G, Noh T W
FPRD, Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea.
Phys Rev Lett. 2006 Dec 15;97(24):247602. doi: 10.1103/PhysRevLett.97.247602.
In most ferroelectrics, the domain nucleation barrier (U*) is thermally insurmountable; this is called "Landauer's paradox." However, we showed that, in ultrathin films, the large depolarization fields could lower U* to a level comparable to thermal energy (k(B)T), resulting in power-law decay of polarization. We empirically found a universal relation between the power-law decay exponent and U*/k(B)T. This relation will provide a practical but fundamental limit for capacitor-type ferroelectric devices, analogous to the superparamagnetic limit for magnetic memory devices.
在大多数铁电体中，畴成核势垒（U*）在热学上是无法逾越的；这被称为“兰道尔悖论”。然而，我们表明，在超薄薄膜中，大的退极化场可将U降低到与热能（k(B)T）相当的水平，从而导致极化的幂律衰减。我们通过实验发现了幂律衰减指数与U/k(B)T之间的普遍关系。这种关系将为电容型铁电器件提供一个实际但基本的限制，类似于磁存储器件的超顺磁极限。
