Strain-Engineered Oxygen Vacancies in CaMnO3 Thin Films

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• 作者：Ravini U. ChandrasenaWeibing Yang ; Qingyu Lei ; Mario U. Delgado-Jaime ; Kanishka D. Wijesekara ; Maryam Golalikhani ; Bruce A. Davidson ; Elke Arenholz ; Keisuke Kobayashi ; Masaaki Kobata ; Frank M. F. de Groot ; Ulrich Aschauer ; Nicola A. SpaldinXiaoxing Xi ; Alexander X. Gray
• 刊名：Nano Letters
• 出版年：2017
• 出版时间：February 8, 2017
• 年：2017
• 卷：17
• 期：2
• 页码：794-799
• 全文大小：413K
• ISSN：1530-6992

文摘

We demonstrate a novel pathway to control and stabilize oxygen vacancies in complex transition-metal oxide thin films. Using atomic layer-by-layer pulsed laser deposition (PLD) from two separate targets, we synthesize high-quality single-crystalline CaMnO₃ films with systematically varying oxygen vacancy defect formation energies as controlled by coherent tensile strain. The systematic increase of the oxygen vacancy content in CaMnO₃ as a function of applied in-plane strain is observed and confirmed experimentally using high-resolution soft X-ray absorption spectroscopy (XAS) in conjunction with bulk-sensitive hard X-ray photoemission spectroscopy (HAXPES). The relevant defect states in the densities of states are identified and the vacancy content in the films quantified using the combination of first-principles theory and core–hole multiplet calculations with holistic fitting. Our findings open up a promising avenue for designing and controlling new ionically active properties and functionalities of complex transition-metal oxides via strain-induced oxygen-vacancy formation and ordering.