[행사/세미나] [Colloquium] Nov. 22(Wed.) Heterostructuring freestanding membranes for functional oxide electronics
이번 학기 열 번째 콜로퀴움은 울산대학교 김태헌 교수님을 모시고 콜로퀴움을 개최하오니, 학과 구성원 여러분의 많은 참여를 부탁 드립니다.
1. Title: Heterostructuring freestanding membranes for functional oxide electronics
2. Speaker: 김 태 헌 교수님 (울산대학교 물리학과)
3. Date & Time: Nov. 22(Wed.) 2023. 4:30 PM
4. Place: Natural Science 1, Room No. 31214
5. Abstract: For last several decades, complex oxides have been served as fertile ground for exploring a wide range of fascinating physical properties scientifically and for developing multi-functional electronic devices with high performance technologically. In functional oxide heterostructures, where complex oxide thin films are epitaxially constrained and clamped by the underlying single crystal substrates, a large variety of control factors arising from a mismatch between order parameters (i.e., lattice structure/symmetry, charge, spin, and orbital) are accessible enabling us to realize emerging physical phenomena which do not exist in nature. Very recently, versatile freestanding oxide membranes have attracted enormous attention to the associated fields with synthesis and characterization of complex oxide thin films due to the excellent functionalities of ultra-flexibility and super-elasticity. More interestingly, it is also possible to artificially design and realize unusual functionalities by heterogeneously integrating some freestanding oxide membranes with different physical properties. Here, we demonstrate heterogeneous integration and/or heteroepitaxial junctions of two freestanding oxide membranes exhibiting advanced functional properties compared with the bulk compounds. To accomplish this, highly crystalline freestanding oxide membranes are successfully exfoliated by selectively etching an infinite-layer SrCuO2 sacrificial layers in epitaxial perovskite oxide (e.g., SrRuO3 and BaZrO3)/SrCuO2 bilayer thin films. Using the oxide membrane templates, various thin-film heterostructures with nano- and micro-scale thickness consisting of functional oxides and membrane templates are heterogeneously integrated with non-oxide host substrates leading to enhancement of eminent physical properties such as ferroelectric polarization, dielectric constant, piezoelectric coefficient, and flexoelectric field. The microscopic mechanisms of the boosted electrical/mechanical responses are also discussed in conjunction with potential applications of the freestanding oxide membranes to next-generation energy harvesting/memory devices as well as rational design of new quantum materials via symmetry engineering.
Keywords—Freestanding membranes; Complex oxides; Thin films; Heterostructures; Functional devices