Hlinka J, Ostapchuk T, Nuzhnyy D, Petzelt J, Kuzel P, Kadlec C, Vanek P, Ponomareva I, Bellaiche L
Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, Prague 8, Czech Republic.
Phys Rev Lett. 2008 Oct 17;101(16):167402. doi: 10.1103/PhysRevLett.101.167402. Epub 2008 Oct 15.
The dielectric response to infrared waves polarized along the tetragonal axis of a ferroelectric single-domain crystal of BaTiO3 was determined by time-domain THz spectroscopy and Fourier-transform infrared reflectivity techniques. In addition to the three well-known polar lattice modes, the experiment shows an additional mode of the relaxation type in the THz spectral region, which accounts for the Curie-Weiss behavior of the c-axis dielectric constant. A comparison of experimental results with ab initio based effective-Hamiltonian simulations allows us to elucidate its relation to the order-disorder model of Comes, Lambert, and Guinier [Solid State Commun. 6, 715 (1968)10.1016/0038-1098(68)90571-1].
通过时域太赫兹光谱和傅里叶变换红外反射率技术，测定了沿钛酸钡铁电单畴晶体四方轴偏振的红外波的介电响应。除了三种众所周知的极性晶格模式外，实验还在太赫兹光谱区域显示了一种额外的弛豫型模式，这解释了c轴介电常数的居里-外斯行为。将实验结果与基于第一性原理的有效哈密顿量模拟进行比较，使我们能够阐明其与Comes、Lambert和Guinier的有序-无序模型的关系[《固体通讯》6, 715 (1968)10.1016/0038-1098(68)90571-1]。
