Skip to main content

ULTRA STEM

Scientific highlights

Atmosphere-Induced Reversible Resistivity Changes in Ca/Y-Doped Bismuth Iron Garnet Thin Films

Resistive changes in Y-substituted bismuth iron garnet (BIG)

Bismuth iron garnet Bi3Fe5O12 (BIG) is a multifunctional insulating oxide exhibiting remarkably the largest known Faraday rotation and linear magnetoelectric coupling. Enhancing the electrical conductivity in BIG while preserving its magnetic properties would further widen its range of potential applications in oxitronic devices. Here, a site-selective co-doping strategy in which Ca2+ and Y3+ substitute for Bi3+ is applied. The resulting p- and n-type doped BIG films combine state-of-the-art magneto-optical properties and semiconducting behaviors above room temperature with rather low resistivity: 40 Ohm cm at 450 K is achieved in an n-type Y-doped BIG; this is ten orders of magnitude lower than that of Y3Fe5O12. High-resolution electron spectromicroscopy unveils the complete dopant solubility and the charge compensation mechanisms at the local scale in p- and n-type systems. Oxygen vacancies as intrinsic donors play a key role in the conduction mechanisms of these doped BIG films. On the other hand, a self-compensation of Ca2+ with oxygen vacancies tends to limit the conduction in p-type Ca/Y-doped BIG. Read more »

Plasmonic quantum size effects in silver nanoparticles are dominated by interfaces and local environments

Campos.jpg

The physical properties of metals change when their dimensions are reduced to the nano-scale and new phenomena such as the localized surface plasmon resonance (LSPR) appear. This collective electronic excitation can be tuned over a large spectral range by adapting the material, size and shape. The existing literature is as rich as it is controversial—for example, size-dependent spectral shifts of the LSPR in small metal nanoparticles, induced by quantum effects, are reported to the red, to the blue or entirely absent. Here we report how complementary experiments on size-selected small silver nanoparticles embedded in silica can yield inconsistent results on the same system: whereas optical absorption shows no size effect in the range between only a few atoms and ~10 nm, a clear spectral shift is observed in single-particle electron spectroscopy. Our quantitative interpretation, based on a mixed classical/quantum model, resolves the apparent contradictions, not only within our experimental data but also in the literature. Our comprehensive model describes how the local environment is the crucial parameter controlling the manifestation or absence of quantum size effects. Read more »

Publications

Karapinar, D., et al. Carbon-Nanotube-Supported Copper Polyphthalocyanine for Efficient and Selective Electrocatalytic CO 2 Reduction to CO. ChemSusChem 110627133819613867946813834931339326416013813910712224519085252, (2019).
Zobelli, A., et al. Spatial and spectral dynamics in STEM hyperspectral imaging using random scan patterns. Ultramicroscopy 112912 (2019).doi:10.1016/j.ultramic.2019.112912
Faye, D.N., et al. Incorporation of Europium Into GaN Nanowires by Ion Implantation. The Journal of Physical Chemistry C (2019).doi:10.1021/acs.jpcc.8b12014
Tizei, L.H.G., et al. Monolayer and thin h –BN as substrates for electron spectro-microscopy analysis of plasmonic nanoparticles. Applied Physics Letters 113122, 231108 (2018). Download: PlamonsOnhBN_APL_2018 .pdf (1.13 MB)
Campos, A., et al. Plasmonic quantum size effects in silver nanoparticles are dominated by interfaces and local environments. Nature Physics (2018).doi:10.1038/s41567-018-0345-z Download: CNP.pdf (1.79 MB)
Lourenço-Martins, H., Das, P., Tizei, L.H.G., Weil, R. & Kociak, M. Self-hybridization within non-Hermitian localized plasmonic systems. Nature Physics 89, (2018). Download: LM2018.pdf (3.41 MB)
Gloter, A., et al. Atomically resolved mapping of EELS fine structures. Materials Science in Semiconductor Processing 65, 2 - 17 (2017). Download: 1-s2.0-S1369800116302165-main.pdf (5.7 MB)
Campos, A., et al. Plasmonic Breathing and Edge Modes in Aluminum Nanotriangles. ACS Photonics (2017).doi:10.1021/acsphotonics.7b00204 Download: Campos2017.pdf (5.45 MB)
Popova, E., et al. Interplay between epitaxial strain and low dimensionality effects in a ferrimagnetic oxide. Journal of Applied Physics 121, (2017). Download: Popova_JAP2017_Strain-STEM-GPA.pdf (4.49 MB)
Tizei, L.H.G. & Kociak, M. Advances in Imaging and Electron PhysicsQuantum Nanooptics in the Electron Microscope. (2017).doi:10.1016/bs.aiep.2017.01.002 Download: Tizei_Kociak_AIE.pdf (3.49 MB)
Mayer, M., et al. Controlled Living Nanowire Growth: Precise Control over the Morphology and Optical Properties of AgAuAg Bimetallic Nanowires. Nano Letters 150716113957008 (2015).doi:10.1021/acs.nanolett.5b01833 Download: Mayer.pdf (6.19 MB)
Arenal, R., et al. Atomic Configuration of Nitrogen-Doped Single-Walled Carbon Nanotubes. Nano Letters 14, 5509 - 5516 (2014).
Tizei, L.H.G., et al. A polarity-driven nanometric luminescence asymmetry in AlN/GaN heterostructures. Applied Physics Letters 105, 143106 (2014). Download: Tizei_GaNQWCLAsymmetry_APL_2014.pdf (1.74 MB)
Bourrellier, R., et al. Nanometric Resolved Luminescence in h-BN Flakes: Excitons and Stacking Order. ACS Photonics 1, (2014). Download: bourrellier-acs-photonics.pdf (7.37 MB)
Walls, M., et al. Identification of Ferrous-Ferric Fe3O4 Nanoparticles in Recombinant Human Ferritin Cages. Microscopy and Microanalysis 19, 835 - 841 (2013).
Yang, Z., Walls, M., Lisiecki, I. & Pileni, M.-P. Unusual Effect of an Electron Beam on the Formation of Core/Shell (Co/CoO) Nanoparticles Differing by Their Crystalline Structures. Chemistry of Materials 25, 2372 - 2377 (2013).
Cha, L., Lartigue-Korinek, S., Walls, M. & Mazerolles, L. Interface structure and chemistry in a novel steel-based composite Fe–TiB2 obtained by eutectic solidification. Acta Materialia 60, 6382 - 6389 (2012).
Chen, S.-Y., et al. Concentration Dependence of Oxygen Vacancy on the Magnetism of CeO 2 Nanoparticles. The Journal of Physical Chemistry C 116, 8707 - 8713 (2012).
Umek, P., et al. Local Coordination and Valence States of Cobalt in Sodium Titanate Nanoribbons. The Journal of Physical Chemistry C 116, 11357 - 11363 (2012).
Eswara Moorthy, S.K., Rousseau, O., Viret, M. & Kociak, M. Nanoscale Chemical and Structural Characterization of Transient Metallic Nanowires using Aberration-Corrected STEM-EELS. Nano Letters 12, 2732 - 2739 (2012). Download: nl204374v.pdf (1.74 MB)
Bocher, L., et al. Atomic and Electronic Structure of the BaTiO 3 /Fe Interface in Multiferroic Tunnel Junctions. Nano Letters 12, 376 - 382 (2012). Download: Bocher-Nanoletters12.pdf (2.76 MB)
Cavalier, M., Walls, M., Lisiecki, I. & Pileni, M.P. How Can the Nanocrystallinity of 7 nm Spherical Co Nanoparticles Dispersed in Solution Be Improved?. Langmuir 27, 5014–5020 (2011).
Trasobares, S., et al. Chemical Imaging at Atomic Resolution as a Technique To Refine the Local Structure of Nanocrystals. Angewandte Chemie-International Edition 50, 868–872 (2011). Download: Angew. Chem. Int. Ed. 2011 Trasobares.pdf (649.98 KB)
Valencia, S., et al. Interface-induced room-temperature multiferroicity in BaTiO3. Nature Materials 10, 753 - 758 (2011). Download: Valencia_NatMat11_XMCD-BTOFe.pdf (761.54 KB)
Garcia, V., et al. Ferroelectric Control of Spin Polarization. Science 327, 1106–1110 (2010). Download: Garcia_Science10_ferroelectric_LSMO-BTO-Fe.pdf (400.27 KB)
Rigutti, L., et al. Ultraviolet Photodetector Based on GaN/AlN Quantum Disks in a Single Nanowire. Nano Letters 10, 2939–2943 (2010).
Sefrioui, Z., et al. All-Manganite Tunnel Junctions with Interface-Induced Barrier Magnetism. Advanced Materials 22, 5029–+ (2010).
Syndicate content