Intriguing domain dynamics in ferroelectric thin films investigated by piezoresponse force microscopy
Ferroelectric (FE) materials possess two peculiarities: the appearance of spontaneous polarization below Curie temperature and the ability to switch between two (or more) polarization states under an external electric field. Due to the electrically switchable spontaneous polarization, FE materials have attracted considerable attention for potential applications in multifunctional electronic devices, such as nonvolatile FE random access memories and FE tunnel junctions. It is therefore very important to understand how polarization switching occurs under an external electric field in FE materials. However, it is quite challenging to probe precisely polarization switching process. First, it is composed of various dynamic steps, including the nucleation of domains with reversed polarization and subsequent domain wall motion. Second, it generally needs both nanoscale length and time resolutions. Here, I want to highlight that one of the most powerful methods to investigate nanoscale domain dynamics is piezoresponse force microscopy (PFM). PFM is based on the atomic force microscopy. It detects the converse piezoresponse induced by applied external ac field, yielding the spatial-resolved FE domain information. In this talk, I will introduce the details of FE materials and PFM. Additionally, I will present the recent results on the intriguing domain dynamics in FE thin films investigated by PFM [1].
* 일시 : 2012년 9월 27일 목요일 오후 4시 30분
* 장소 : 베어드홀 102호
* 연사 : 양 상 모 박사 (서울대 물리천문학부)