Research Themes

Theme 2

The Institute's research in Electronic and Optical Materials is undertaken at the School of Chemical & Physical Sciences, Victoria University of Wellington.

Theme 2 Outputs

Investigators and researchers

Graduate Students

Theme 2: Electronic and Optical Materials

Theme Leader: Dr. Ben Ruck

Overview

Theme 2 Objectives





Overview

  • Strongly correlated electron systems Our objective in the next 2 years is to research Fe-based compounds that display a range of phenomena that includes partial charge-ordering, colossal magneto-resistance, magnetic order, spin-frustration, and multi-ferroic behavior. We will focus on SrFeOx, FeSr2RCu2O8, FeSr2R2-xCexCu2O10+x, and BiFeO3, where R is a rare earth.
  • High-temperature superconductors and related materials To use muon spin relaxation, NMR and synchrotron x-ray measurements in HTS cuprates to probe the slowing down of spin fluctuations within a quantum critical point scenario when the electronic system is prone to elecronic phase separation; and to continue the search for novel hybrid oxide superconductors.
  • Electronic transport in novel materials: from macro-to-nanoscale Our work upon carbon nanotube films has enabled us to build an in-depth understanding of temperature-dependent electron transport in disordered nanowire networks. We will continue to build on this work and move to examining two new classes of materials: semiconductor nanowire networks (indium phosphide, germanium), and metal nanoparticle/CNT composite films. Further work will be aimed at understanding electronic transport in graphene, a new form of carbon, consisting of a single layer of carbon atoms that has many unique properties. This system will be examined in collaboration with colleagues at the Max Planck Institute, Stuttgart.
  • Optoelectronic properties of rare-earth nitrides We will investigate the optoelectronic properties of rare-earth nitride thin films. Several members of the rare-earth nitride series are known to be semiconducting, and we will measure their electrical conductivity and photoconductivity at room temperature and in their low-temperature magnetic phase. The results will be interpreted in terms of modern band structure calculations, and in terms of models of the crystalline defects in the materials. Work will initially focus on gadolinium, samarium and lutetium nitride.
  • Ferroelectric perovskites: Raman spectroscopy We will determine the phase diagram and dynamic fluctuations in bulk and nanostructured perovskite ferroelectrics. These materials may be substitutes for Pb-bearing ferroelectrics (PZT, (Pb.Zr)TaO3) currently in widespread use, and more widely they are model systems for the effects of fluctuations on a large range of ferromagnetic, ferroelectric and superconducting materials. It will be necessary to perform experiments to temperatures from 5 K to 900 K, using both visible and UV excitation. In the longer term it will be especially useful to perform experiments to high pressure.
  • Structural and optical properties of insulating superlattices Our objective in the next period is to understand the mechanism of photoionisation and subsequent electron trapping in fluoride superlattices. The difference between trapping by tunnelling through the bandgap barriers and trapping at defect sites will be investigated. The results will contribute to understanding charge transport properties in wide-band gap optical materials.
  • Novel optical materials: Glass-ceramics and optical amplifi cation We will investigate rare-earth doped glass ceramics from the perspective of potential optical gain media, focussing on the effect of particle size on radiative lifetimes with the aid of the new fluorolog and SAXS instruments. The materials used will be selected from the two extremes of ultratransparency and opacity, representing potential fibre lasing and random lasing materials respectively.

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Theme 2 Objectives

  1. Strongly correlated electron systems (G.V.M. Williams, B. Ruck, J.L. Tallon)
  2. High-temperature superconductors and related materials (J.L. Tallon, G.V.M. Williams)
  3. Electronic transport in novel materials: from macro-to-nanoscale (A.B. Kaiser, U. Zülicke, M. Alkaisi, R. Tilley)
  4. Optoelectronic properties of rare-earth nitrides (B. Ruck, H.J. Trodahl, S.M. Durbin, R.J. Reeves, J. Dunlop)
  5. Raman spectroscopy of ferroelectric perovskites (H.J. Trodahl, P.G. Etchegoin, B. Ruck, G.V.M. Williams)
  6. Structural and optical properties of insulating superlattices (R.J. Reeves)
  7. Novel optical materials: Glass-ceramics and optical amplification (A. Edgar, G.V.M. Williams)
  8. Optical properties in mixed metal oxides/oxynitrides (J. Metson)

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