Persistence of Ferroelectricity in BaTiO3 through the Insulator-Metal Transition
Persistence of Ferroelectricity in BaTiO3 through the Insulator-Metal Transition
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DOI：
10.1103/physrevlett.104.147602
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发表时间：
2010-04-09
影响因子：
8.6
通讯作者：
Takayama-Muromachi, E.
中科院分区：
文献类型：
--
作者：
Kolodiazhnyi, T.;Tachibana, M.;Takayama-Muromachi, E.
铁电 BaTiO3 是一种带隙绝缘体。可以通过掺杂例如氧空位将巡回电子引入到该材料中。高于临界电子浓度 n(c) 时大约为 1 x 10(20) cm(-3)。 BaTiO3-δ 变成金属。这就立即提出了一个问题：金属 BaTiO3-δ 是否仍保留铁电性？人们可能期望流动电子在屏蔽长程库仑相互作用时会破坏铁电性。我们跟踪 BaTiO3-δ 中的相变作为 n 的函数，直至进入金属相。尽管它们的稳定范围随着n的增加而减小，但金属BaTiO3-δ中的低对称性相仍然保留到n*的估计浓度接近1.9 x 10(21) cm(-3)。此外，巡回电子似乎通过屏蔽氧空位引起的强晶体场扰动部分稳定了金属 BaTiO3-δ 中的铁电相。
The ferroelectric BaTiO3 is a band-gap insulator. Itinerant electrons can be introduced in this material by doping, for example, with oxygen vacancies. Above a critical electron concentration of n(c) approximate to 1 x 10(20) cm(-3). BaTiO3-delta becomes metallic. This immediately raises a question: Does metallic BaTiO3-delta still retain ferroelectricity? One may expect itinerant electrons to destroy ferroelectricity as they screen the long-range Coulomb interactions. We followed the phase transitions in BaTiO3-delta as a function of n far into metallic phase. Although their stability range decreases with n, the low-symmetry phases in metallic BaTiO3-delta are still retained up to an estimated concentration of n* approximate to 1.9 x 10(21) cm(-3). Moreover, it appears that the itinerant electrons partially stabilize the ferroelectric phases in metallic BaTiO3-delta by screening strong crystal field perturbations caused by oxygen vacancies.