Creation and control of a two-dimensional electron liquid at the bare SrTiO3 surface
Creation and control of a two-dimensional electron liquid at the bare SrTiO3 surface
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DOI：
10.1038/nmat2943
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发表时间：
2011-02-01
期刊：
影响因子：
41.2
通讯作者：
Shen, Z-X.
中科院分区：
文献类型：
--
作者：
Meevasana, W.;King, P. D. C.;Shen, Z-X.
过渡金属氧化物中的多体相互作用产生了广泛的功能特性，例如高温超导性 (1)、巨磁阻 (2) 或多铁性 (3)。最近在绝缘氧化物 LaAlO3 和 SrTiO3 界面处发现了二维电子气 (2DEG)（参考文献 4），这一开创性的发现代表了在全氧化物器件中利用此类特性的一个重要里程碑 (5)。这种导电界面显示出许多吸引人的特性，包括高电子迁移率 (4,6)、超导性 (7) 和大磁阻 (8)，并且可以在几纳米长度尺度上进行图案化。然而，人们对 2DEG 界面的微观起源知之甚少。在这里，我们表明，可以在裸露的 SrTiO3 表面形成电子密度高达 8 x 10(13) cm(-2) 的类似 2DEG。此外，我们发现可以通过将表面暴露在强紫外线下来控制 2DEG 密度。随后的角分辨光电子能谱测量揭示了轻准粒子质量和强多体相互作用特征的不寻常共存。
Many-body interactions in transition-metal oxides give rise to a wide range of functional properties, such as high-temperature superconductivity(1), colossal magnetoresistance(2) or multiferroicity(3). The seminal recent discovery of a two-dimensional electron gas (2DEG) at the interface of the insulating oxides LaAlO3 and SrTiO3 (ref. 4) represents an important milestone towards exploiting such properties in all-oxide devices(5). This conducting interface shows a number of appealing properties, including a high electron mobility(4,6), superconductivity(7) and large magnetoresistance(8), and can be patterned on the few-nanometre length scale. However, the microscopic origin of the interface 2DEG is poorly understood. Here, we show that a similar 2DEG, with an electron density as large as 8 x 10(13) cm(-2), can be formed at the bare SrTiO3 surface. Furthermore, we find that the 2DEG density can be controlled through exposure of the surface to intense ultraviolet light. Subsequent angle-resolved photoemission spectroscopy measurements reveal an unusual coexistence of a light quasiparticle mass and signatures of strong many-body interactions.