Observation of charge density waves in free-standing 1T-TaSe2 monolayers by transmission electron microscopy
Observation of charge density waves in free-standing 1T-TaSe2 monolayers by transmission electron microscopy
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DOI：
10.1063/1.5052722
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发表时间：
2018-10
影响因子：
4
通讯作者：
P. Börner;M. Kinyanjui;T. Björkman;T. Lehnert;A. Krasheninnikov;U. Kaiser
中科院分区：
文献类型：
--
作者：
P. Börner;M. Kinyanjui;T. Björkman;T. Lehnert;A. Krasheninnikov;U. Kaiser
虽然体块1T-TaSe2在473 K以下具有相称电荷密度波（CCDW）状态，但CCDW状态在1T-TaSe2单层中的稳定性虽然在理论上得到了预测，但迄今尚未得到实验证实。由于电荷密度波和周期性晶格畸变（PLD）总是一起出现，我们通过低压像差校正的高分辨率透射电子显微镜实验来评估1T-TaSe2单层中的PLD。为了防止1T-TaSe2在电子束下的快速降解，制备了1T-TaSe2/石墨烯异质结构。我们还基于密度泛函理论计算得到的原子坐标进行了图像模拟。从实验和模拟图像的一致性来看，我们证实了CCDW/PLD在单层1T-TaSe2/石墨烯异质结构中以13 × 13上层结构的形式在室温下的稳定性。与此同时，我们发现与多层结构相比，上层结构不太明显。虽然体块1T-TaSe2在473 K以下具有相称电荷密度波（CCDW）状态，但CCDW状态在1T-TaSe2单层中的稳定性虽然在理论上得到了预测，但迄今尚未得到实验证实。由于电荷密度波和周期性晶格畸变（PLD）总是一起出现，我们通过低压像差校正的高分辨率透射电子显微镜实验来评估1T-TaSe2单层中的PLD。为了防止1T-TaSe2在电子束下的快速降解，制备了1T-TaSe2/石墨烯异质结构。我们还基于密度泛函理论计算得到的原子坐标进行了图像模拟。从实验和模拟图像的一致性来看，我们证实了CCDW/PLD在单层1T-TaSe2/石墨烯异质结构中以13 × 13上层结构的形式在室温下的稳定性。与此同时，我们发现与多层结构相比，…
While bulk 1T-TaSe2 is characterized by a commensurate charge density wave (CCDW) state below 473 K, the stability of the CCDW state in a 1T-TaSe2 monolayer, although theoretically predicted, has not been experimentally confirmed so far. As charge density waves and periodic lattice distortions (PLDs) always come together, we evaluate the PLD in a 1T-TaSe2 monolayer from low-voltage aberration-corrected high-resolution transmission electron microscopy experiments. To prevent fast degradation of 1T-TaSe2 during exposure to the electron-beam, a 1T-TaSe2/graphene heterostructure was prepared. We also perform the image simulations based on atom coordinates obtained using density functional theory calculations. From the agreement between the experimental and simulated images, we confirm the stability of the CCDW/PLD in a monolayer 1T-TaSe2/graphene heterostructure at room temperature in the form of a 13 × 13 superstructure. At the same time, we find that in comparison to multi-layer structures, the superstructure is less pronounced.While bulk 1T-TaSe2 is characterized by a commensurate charge density wave (CCDW) state below 473 K, the stability of the CCDW state in a 1T-TaSe2 monolayer, although theoretically predicted, has not been experimentally confirmed so far. As charge density waves and periodic lattice distortions (PLDs) always come together, we evaluate the PLD in a 1T-TaSe2 monolayer from low-voltage aberration-corrected high-resolution transmission electron microscopy experiments. To prevent fast degradation of 1T-TaSe2 during exposure to the electron-beam, a 1T-TaSe2/graphene heterostructure was prepared. We also perform the image simulations based on atom coordinates obtained using density functional theory calculations. From the agreement between the experimental and simulated images, we confirm the stability of the CCDW/PLD in a monolayer 1T-TaSe2/graphene heterostructure at room temperature in the form of a 13 × 13 superstructure. At the same time, we find that in comparison to multi-layer structures, the...