[26a-E307-1~9] 9.1 誘電材料・誘電体

▲ [26a-E307-1] Basic Mechanism and Potential Application of Ferroelectric Quantum Phase Transition: The Representative Case of SrTiO₃

〇(P)Dongxiao Fan¹、Shunsuke Nozawa¹、Nobuo Nakajima²、Andris Anspoks³、Takafumi Miyanaga⁴ (1.KEK、2.Hiroshima Univ.、3.Latvia Univ.、4.Hirosaki Univ.)

キーワード：Ferroelectric Quantum Phase Transition, EXAFS, Symmetry-breaking

We study the low-temperature ferroelectric quantum phase transition of SrTiO₃. SrTiO₃ is perfectly centrosymmetric in macroscopic scale in the whole temperature range. The local structure within the scale of several unit cells is unclear. At low temperature, SrTiO₃ possesses quantum paraelectricity with multitudinous physical properties, which attracts a lot of attention. We use extended X-ray absorption fine structure (EXAFS) to study the local structure of SrTiO₃ and its doped variants (SrTi¹⁸O₃ and Sr_1-xCa_xTiO₃). The results show SrTiO₃ has a non-centrosymmetric local structure and the ferroelectric quantum phase transition of SrTi¹⁸O₃ and Sr_1-xCa_xTiO₃ was confirmed by investigating the relative vibration of the atoms. The small non-centrosymmetric local structure of SrTiO₃ and low-temperature phase transition can be used to manufacture electronic devices with special functions, such as radiation-hardness of ferroelectric memories, and array radar devices.