laser-induced-forward-transfer-of-ag-nanopaste

Laser-induced Forward Transfer of Ag Nanopaste

Over the past decade, there has been much development of non-lithographic methods1-3 for printing metallic inks or other functional materials. Many of ...

Naval Research Laboratory

The combination of epitaxial strain and defect engineering facilitates the tuning of the transition temperature of BaTiO3 to >800 °C. Advances in thin-film deposition enable the utilization of both the electric and elastic dipoles of defects to extend the epitaxial strain to new levels, inducing unprecedented functionality and temperature stability in ferroelectrics.

Enhancement of ferroelectric Curie temperature in BaTiO3 films via strain-induced defect dipole alignment.

Next-generation devices will rely on exotic functional properties not found in traditional systems. One class of materials of particular interest for applications are those possessing metal-to-insulator transitions (MITs). In this work, we probe the relationship between variations in the growth process, subsequent variations in cation stoichiometry, and the MIT in NdNiO3 thin films. Slight variations in the growth conditions, in particular the laser fluence, during pulsed-laser deposition growth of NdNiO3 produces films that are both single-phase and coherently strained to a range of substrates despite possessing as much as 15% Nd-excess. Subsequent study of the temperature-dependence of the electronic transport reveals dramatic changes in both the onset and magnitude of the resistivity change at the MIT with increasing cation nonstoichiometry giving rise to a decrease (and ultimately a suppression) of the transition and the magnitude of the resistivity change. From there, the electronic transport of nearly ideal NdNiO3 thin films are studied as a function of epitaxial strain, thickness, and orientation. Overall, transitioning from tensile to compressive strain results in a systematic reduction of the onset and magnitude of the resistivity change across the MIT, thinner films are found to possess sharper MITs with larger changes in the resistivity at the transition, and (001)-oriented films exhibit sharper and larger MITs as compared to (110)- and (111)-oriented films as a result of highly anisotropic in-plane transport in the latter.

Effects of nonequilibrium growth, nonstoichiometry, and film orientation on the metal-to-insulator transition in NdNiO₃ thin films.

Sr2Ti7O14, a new phase, is synthesized by leveraging the innate chemical and thermo-dynamic instabilities in the SrTiO3-TiO2 system and non-equilibrium growth techniques. The chemical composition, epitaxial relationships, and orientation play roles in the formation of this novel layered phase, which, in turn, possesses unusual charge ordering, anti-ferromagnetic ordering, and low, glass-like thermal conductivity.

A novel, layered phase in Ti-rich SrTiO3 epitaxial thin films.

We report intense, narrow line-width, surface chemisorption-activated and reversible ultraviolet (UV) photoluminescence from radiative recombination of the two-dimensional electron gas (2DEG) with photoexcited holes at LaAlO3/SrTiO3. The switchable luminescence arises from an electron transfer-driven modification of the electronic structure via H-chemisorption onto the AlO2-terminated surface of LaAlO3, at least 2 nm away from the interface. The control of the onset of emission and its intensity are functionalities that go beyond the luminescence of compound semiconductor quantum wells. Connections between reversible chemisorption, fast electron transfer, and quantum-well luminescence suggest a new model for surface chemically reconfigurable solid-state UV optoelectronics and molecular sensing.

Surface Chemically Switchable Ultraviolet Luminescence from Interfacial Two-Dimensional Electron Gas.

VO<sub>2</sub> is a promising material for reconfigurable photonic devices due to the ultrafast changes in electronic and optical properties associated with its dielectric-to-metal phase transition. Based on a fiber-optic, pump-probe setup at 1550 nm wavelength window, and by varying the pump-pulse duration, we show that the material phase transition is primarily caused by the pump-pulse energy. For the first time, we demonstrate that the instantaneous optical phase modulation of probe during pump leading edge can be utilized to create short optical pulses at probe wavelength, through optical frequency discrimination. This circumvents the impact of long recovery time well known for the phase transition of VO<sub>2</sub>.

Article	Year
Enhancement of ferroelectric Curie temperature in BaTiO3 films via strain-induced defect dipole alignment. Advanced materials (Deerfield Beach, Fla.)\| PubMed ID: 25099557	2014
Effects of nonequilibrium growth, nonstoichiometry, and film orientation on the metal-to-insulator transition in NdNiO₃ thin films. ACS applied materials & interfaces\| PubMed ID: 25454898	2014
A novel, layered phase in Ti-rich SrTiO3 epitaxial thin films. Advanced materials (Deerfield Beach, Fla.)\| PubMed ID: 25523179	2015
Surface Chemically Switchable Ultraviolet Luminescence from Interfacial Two-Dimensional Electron Gas. Nano letters\| PubMed ID: 26675987	2016
All-optical short pulse translation through cross-phase modulation in a VO<sub>2</sub> thin film. Optics letters\| PubMed ID: 26766683	2016

Eric Breckenfeld

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