講演情報
[24p-P05-15]Detecting the Quantum Ferroelectric Phase Transition of Doped Quantum Paraelectrics by Multiple-edge XAFS
〇(P)Dongxiao Fan1, Shunsuke Nozawa1, Rie Haruki1, Youngmin Kim1 (1.KEK)
キーワード：
Quantum ferroelectric phase transition、EXAFS、Dynamic polarization
SrTiO3 the representative of transition-metal oxides in the family of perovskite compounds, which has an irreplaceable role in condensed matter physics for its multitudinous physical properties. SrTiO3 holds the perfectly centrosymmetric in macroscopic scale in the whole temperature range. At low temperature (< 50 K), SrTiO3 possesses the quantum paraelectric phase, which is caused by the competing between electric dipole moment and the quantum fluctuations. With 18O substitution of the 16O, SrTi18O3 undergoes a quantum ferroelectric phase transition below 23K. We use extended X-ray absorption fine structure (EXAFS) to study the local structure of SrTi16O3 and SrTi18O3. The MSRD of SrTi18O3 is increased comparing with SrTi16O3 below Tc (23 K), which means the correlated movement between Ti and O is reduced with 18O substitution. The PDF of SrTi16O3 at 004 K shows no splitting of the Ti-O bond, but in SrTi18O3 clear Ti-O bond splitting are observed, which indicates the triumph of the electric dipole moment against the quantum fluctuation. The small non-centrosymmetric local structure of SrTi18O3 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.The same experiment is also conducted for other doped quantum paraelectrics Sr1-xCaxTiO3, Ag1-xLixTaO3, and Cd1-xCaxTiO3. The same MSRD variation is observed.