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에피 산화물연구실에서 Los Alamos National Laboratory 강경태 박사님을 초청하여 아래와 같이 세미나를 개최합니다.

학과 구성원 여러분의 많은 참석을 부탁 드립니다.

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Date/time: 2021. 1. 14 (Thu.) 10:00

Speaker:     태 박사님 (Los Alamos National Laboratory)

Title: Oxygen sponge effects for epitaxial manganite thin film design

Abstract: Ever since the development of high-temperature superconducting thin films, pulsed laser deposition (PLD) has played a central role in realizing high-quality complex oxides. In complex oxide thin films, heterostructure, and nanocomposites, the PLD has been widely utilized for various properties such as ferroelectricity, magnetism. Among the PLD parameters, background oxygen gas and oxide target have been known as the primary oxygen sources to determine the oxygen amount within oxides. So, most conventional oxide films are deposited in the relatively high oxygen partial pressure (50~250 mTorr). Meanwhile, some oxide heterostructures require low oxygen partial pressure, and herein the oxygen vacancies are hardly removed due to the entanglement with the cation off-stoichiometry. In turn, it is extensively demanded to develop a parameter of controlling the oxygen content regardless of the growth pressure, by which enough oxygen can be supply to films for full oxidation even in the low oxygen pressure growth.

Here, we propose the oxygen sponge effect's hypothesis in controlling the oxygen content within the films by using the La0.7Sr0.3MnO3 system [1]. The pre-substrate-annealing (PSA) helps the oxide substrate serve as an oxygen sponge, providing an oxygen-rich or oxygen-poor environment for the film growth. During the PSA, the substrate is heated up in a given oxygen partial pressure right before the film deposition. Moreover, depending on the PSA conditions, the remarkable changes in oxygen content, structure, and functionalities in the as-grown oxide films emerge. The substrate oxygen sponge effect, with the large oxygen concentration gradient at high temperatures, can be applied for emergent interfacial phenomena and the growth of functional oxide thin films and nanocomposites.

[1] K. T. Kang et al., Appl. Phys. Lett. 117, 151601 (2020).

 

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