Photoinduced dynamics in pure and Ca-doped SrTiO_3 studied by transient birefringence and absorption measurements
Photoinduced dynamics in pure and Ca-doped SrTiO_3 studied by transient birefringence and absorption measurements
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通过瞬态双折射和吸收测量研究纯 SrTiO_3 和掺钙 SrTiO_3 的光致动力学
DOI：
10.1143/jpsj.80.104605
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
K.Tanaka
中科院分区：
文献类型：
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作者：
T.Kohmoto;Y.Koyama;T.Moriyasu;H.Okamura;Y.Yamada;K.Tanaka
通过稳态和瞬态双折射以及泵浦-探测测量，研究了SrTiO 3中晶格形变和弛豫激发态的光致动力学，并与Ca掺杂SrTiO 3中掺杂诱导的铁电晶格形变进行了比较. Ca掺杂的SrTiO_3在低阈值紫外光强度（≤ 10 ~（-3）mW/mm ~ 2）下表现出类一阶结构形变，并且在紫外光照射下表现出铁电转变温度的漂移.光致晶格形变与铁电晶格形变具有相同的数量级，并且不受电场的影响。在松弛的激发态的占据概率被发现在低温下显着增加。这些实验结果表明，SrTiO 3的光致巨介电响应符合导电区模型，而不是铁电团簇模型。SrTiO 3是一种特殊的材料，其中Maxwell-Wagner型介电性仅在紫外光照射下出现在化学计量材料中。
The photoinduced dynamics of the lattice deformation and the relaxed excited state in SrTiO3is studied by stationary- and transient-birefringence and pump–probe measurements in comparison with the doping-induced ferroelectric lattice deformation in Ca-doped SrTiO3. Ca-doped SrTiO3is found to exhibit first-order-like structural deformation with a small threshold UV intensity (∼10-3mW/mm2), and it is also found to exhibit a shift in the ferroelectric transition temperature under UV illumination. The photoinduced lattice deformation has the same order of magnitude as the ferroelectric lattice deformation, and it is not affected by the electric field. The occupation probability in the relaxed excited state is found to increase significantly at low temperatures. These experimental results suggest that the photoinduced giant dielectric response of SrTiO3is consistent with the conductive-region model rather than the ferroelectric cluster model. SrTiO3is a peculiar material in which dielectricity of the Maxwell–Wagner type appears in a stoichiometric material only under UV illumination.