Oxygen content tailored magnetic and electronic properties in cobaltite double perovskite thin films

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While pyrochlore iridate thin films are theoretically predicted to possess a variety of emergent topological properties, experimental verification of these predictions can be obstructed by the challenge in thin film growth. Here we report on the pulsed laser deposition and characterization of thin films of a representative pyrochlore compound Bi2Ir2O7. The films were epitaxially grown on yttria-stabilized zirconia substrates and have lattice constants that are a few percent larger than that of the bulk single crystals. The film composition shows a strong dependence on the oxygen partial pressure. Density-functional-theory calculations indicate the existence of BiIr antisite defects, qualitatively consistent with the high Bi: Ir ratio found in the films. Both Ir and Bi have oxidation states that are lower than their nominal values, suggesting the existence of oxygen deficiency. The iridate thin films show a variety of intriguing transport characteristics, including multiple charge carriers, logarithmic dependence of resistance on temperature, antilocalization corrections to conductance due to spin-orbit interactions, and linear positive magnetoresistance.

Section: Pld Growth Structural and Compositional Characterizationsmentioning

confidence: 86%

Epitaxial thin films of pyrochlore iridate Bi2+xIr2-yO7-δ: structure, defects and transport properties

Yang

Xie

Zhu

et al. 2017

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“…There have been tremendous efforts to understand the effect of changes in oxygen content on the properties of perovskite thin films that are not composed of cations with multiple valance states. While oxygen vacancies have been recently been reported to act as desired defects 9 10 11 12 13 14 15 16 17 , the oxygen content effect in perovskite compounds with multiple valance states at the B site can provide a deeper understanding of the underlying mechanics of the functional properties observed in these materials 18 .…”

mentioning

confidence: 99%

Oxygen Vacancy-Tuned Physical Properties in Perovskite Thin Films with Multiple B-site Valance States

Enriquez

Chen

Harrell

et al. 2017

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Controlling oxygen content in perovskite oxides with ABO3 structure is one of most critical steps for tuning their functionality. Notably, there have been tremendous efforts to understand the effect of changes in oxygen content on the properties of perovskite thin films that are not composed of cations with multiple valance states. Here, we study the effect of oxygen vacancies on structural and electrical properties in epitaxial thin films of SrFeO3−δ (SFO), where SFO is a compound with multiple valance states at the B site. Various annealing treatments are used to produce different oxygen contents in the films, which has resulted in significant structural changes in the fully strained SFO films. The out-of-plane lattice parameter and tetragonality increase with decreasing oxygen concentration, indicating the crystal structure is closely related to the oxygen content. Importantly, variation of the oxygen content in the films significantly affects the dielectric properties, leakage conduction mechanisms, and the resistive hysteresis of the materials. These results establish the relationship between oxygen content and structural and functional properties for a range of multivalent transition metal oxides.

“…Figure 2(a,b) show the X-Ray diffraction pattern for the 50 nm VO 2 thin films before and after annealing. It was observed from the graph that the (020) peak of VO 2 was shifted towards a higher 2θ angle upon annealing indicating a possible increase in the oxygen concentration in the films caused by filling up of the oxygen vacancies in the films upon annealing [34][35][36] . Figure 1.…”

Section: Resultsmentioning

confidence: 99%

Reduced Transition Temperature in Al:ZnO/VO2 Based Multi-Layered Device for low Powered Smart Window Application

Behera

Williams

Pradhan

et al. 2020

The metal-to-insulator transition (MIT) closest to room temperature of 68-70 °C as shown by vanadium oxide (Vo 2), compared with other transition metal oxides, makes it a potential candidate for smart window coating. We have successfully fabricated a potential smart window device after the optimum design of a multilayered thin film structure made out of transparent conducting oxide (aluminum doped zinc oxide) and pure Vo 2 using pulsed laser deposition technique. This comprehensive study is based on two different configurations for multi-layered structure approach, with the intention to reduce the transition temperature, as well as to maintain the Mit properties that would strengthen the potential of the structure to be used for a smart window device. By creating a multi-layered structure, we were able to create a low powered device that can operate less than 15 V that leads to significant decline in the infrared transmission by a magnitude of over 40% and provided sufficient heat to trigger the MIT at a temperature around 60 °C, which is almost 10 °C lower than its bulk counterpart. This finding would positively impact the research on Vo 2 thin films, not only as smart windows but also for numerous other applications like bolometers, infrared detectors, Mott transistors and many more.