Ahn Youngjun, Park Joonkyu, Pateras Anastasios, Rich Matthew B, Zhang Qingteng, Chen Pice, Yusuf Mohammed H, Wen Haidan, Dawber Matthew, Evans Paul G
Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA.
Phys Rev Lett. 2017 Aug 4;119(5):057601. doi: 10.1103/PhysRevLett.119.057601. Epub 2017 Jul 31.
The nanodomain pattern in ferroelectric-dielectric superlattices transforms to a uniform polarization state under above-band-gap optical excitation. X-ray scattering reveals a disappearance of domain diffuse scattering and an expansion of the lattice. The reappearance of the domain pattern occurs over a period of seconds at room temperature, suggesting a transformation mechanism in which charge carriers in long-lived trap states screen the depolarization field. A Landau-Ginzburg-Devonshire model predicts changes in lattice parameter and a critical carrier concentration for the transformation.
在带隙以上的光激发下，铁电 - 介电超晶格中的纳米畴图案转变为均匀极化状态。X射线散射显示畴漫散射消失以及晶格膨胀。在室温下，畴图案会在数秒内重新出现，这表明存在一种转变机制，即处于长寿命陷阱态的电荷载流子屏蔽了去极化场。朗道 - 金兹堡 - 德文希尔模型预测了转变过程中晶格参数的变化以及临界载流子浓度。
