INVESTIGATIONS OF STRONGLY-CORRELATED COMPLEX METAL OXIDES AND INTERFACES USING SYNCHROTRON X-RAY SPECTROSCOPY
Author | : Ravini Udeshika Chandrasena |
Publisher | : |
Total Pages | : 154 |
Release | : 2019 |
ISBN-10 | : OCLC:1280139956 |
ISBN-13 | : |
Rating | : 4/5 (56 Downloads) |
Download or read book INVESTIGATIONS OF STRONGLY-CORRELATED COMPLEX METAL OXIDES AND INTERFACES USING SYNCHROTRON X-RAY SPECTROSCOPY written by Ravini Udeshika Chandrasena and published by . This book was released on 2019 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this dissertation, we used a combination of several synchrotron-based x-ray spectroscopic techniques to investigate the effects of strain, ionic defect formation, and heteroengineering in strongly-correlated electronic systems. First, we introduce a method to control and stabilize oxygen vacancies in complex transition-metal oxide thin films. In our approach, we utilized atomic layer-by-layer pulsed laser deposition (ALL laser PLD) from two separate targets to synthesize high-quality single crystalline CaMnO3 films under coherent tensile strain, varying systematically from +0.8% to +4%. An increase of the oxygen vacancy content in the single-crystalline CaMnO3 thin films with applied in-plane strain was experimentally observed using high-resolution soft x-ray absorption spectroscopy (XAS) in conjunction with bulk-sensitive hard x-ray photoelectron spectroscopy (HAXPES). Our experimental results were verified using first-principles theory and atomic core-hole multiplet calculations. Furthermore, our results highlight the importance of protecting the surfaces of CaMnO3 thin-films with thin Pt layers in-situ in order to stabilize the oxygen vacancy content. Next, we discuss the role of oxygen vacancies in driving the metal-insulator transition in LaNiO3 thin films. Here, we also use atomic layer-by-layer pulsed laser deposition (ALL laser PLD) from two separate targets to synthesize high-quality single-crystalline LaNiO3 films with systematically varying thicknesses, ranging from 1 u.c. to 50 u.c. An increase in the oxygen vacancy content was observed with the decreasing LaNiO3 film thickness using XAS. A higher concentration of oxygen vacancies was observed for the ultrathin insulating films (