Oxygen vacancy is intrinsically coupled with magnetic, electronic, and transport properties of transition-metal oxide materials and directly determines their multifunctionality. Here, we demonstrate reversible control of oxygen content by postannealing at temperature lower than 300 °C and realize the reversible metal-insulator transition in epitaxial NdNiO₃ films. Importantly, over 6 orders of magnitude in the resistance modulation and a large change in optical bandgap are demonstrated at room temperature without destroying the parent framework and changing the p-type conductive mechanism. Further study revealed that oxygen vacancies stabilized the insulating phase at room temperature is universal for perovskite nickelate films. Acting as electron donors, oxygen vacancies not only stabilize the insulating phase at room temperature, but also induce a large magnetization of ∼50 emu/cm³ due to the formation of strongly correlated Ni²⁺ t(2g)⁶e(g)² states. The bandgap opening is an order of magnitude larger than that of the thermally driven metal-insulator transition and continuously tunable. Potential application of the newly found insulating phase in photovoltaics has been demonstrated in the nickelate-based heterojunctions. Our discovery opens up new possibilities for strongly correlated perovskite nickelates.
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http://dx.doi.org/10.1021/acsami.6b00650 | DOI Listing |
Adv Sci (Weinh)
December 2024
Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea.
Bioinspired sensory systems based on spike neural networks have received considerable attention in resolving high energy consumption and limited bandwidth in current sensory systems. To efficiently produce spike signals upon exposure to external stimuli, compact neuron devices are required for signal detection and their encoding into spikes in a single device. Herein, it is demonstrated that Mott oscillative spike neurons can integrate sensing and ceaseless spike generation in a compact form, which emulates the process of evoking photothermal sensing in the features of biological photothermal nociceptors.
View Article and Find Full Text PDFMicrosyst Nanoeng
December 2024
Micro- and Nanosystems, Department of Electrical Engineering, KU Leuven, Kasteelpark Arenberg 10, 3001, Leuven, Belgium.
Cr-doped VO thin film shows a huge resistivity change with controlled epitaxial strain at room temperature as a result of a gradual Mott metal-insulator phase transition with strain. This novel piezoresistive transduction principle makes Cr-doped VO thin film an appealing piezoresistive material. To investigate the piezoresistivity of Cr-doped VO thin film for implementation in MEMS sensor applications, the resistance change of differently orientated Cr-doped VO thin film piezoresistors with external strain change was measured.
View Article and Find Full Text PDFNano Lett
December 2024
Department of Physics, Emory University, Atlanta, Georgia 30322, United States.
SrIrO is a metallic complex oxide with unusual electronic and magnetic properties believed to originate from electron correlations due to its proximity to the Mott metal-insulator transition. However, the nature of its electronic state and the mechanism of metallic conduction remain poorly understood. We demonstrate that the shot noise produced by nanoscale SrIrO junctions is strongly suppressed, inconsistent with diffusive quasiparticle transport.
View Article and Find Full Text PDFNanophotonics
September 2024
Center for Theoretical Physics of Complex Systems, Institute for Basic Science (IBS), 34126, Daejeon, Republic of Korea.
Nanophotonics
August 2024
Key Laboratory of Optoelectronic Technology & Systems, Ministry of Education, and College of Optoelectronic Engineering, Chongqing University, Chongqing 400044, China.
Interference between the electric and magnetic dipole-induced in Mie nanostructures has been widely demonstrated to tailor the scattering field, which was commonly used in optical nano-antennas, filters, and routers. The dynamic control of scattering fields based on dielectric nanostructures is interesting for fundamental research and important for practical applications. Here, it is shown theoretically that the amplitude of the electric and magnetic dipoles induced in a vanadium dioxide nanosphere can be manipulated by using laser-induced metal-insulator transitions, and it is experimentally demonstrated that the directional scattering can be controlled by simply varying the irradiances of the excitation laser.
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