Primary Research Activities

Primary Research Activities

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Superconductivity

  • competing orders, pseudogap phenomena, pairing symmetry and pairing mechanism of high-temperature superconducting cuprates
  • magnetic field-induced microscopic orders and quantum fluctuations in cuprate superconductors
  • competing orders, pairing symmetry, pairing mechanism and low-energy quasiparticle excitations in iron-based superconductors
  • non-equilibrium superconductivity associated with excess charge and spin injection into the cuprate superconductors
  • vortex phases and dynamics of high-temperature and conventional amorphous superconductors, from DC to radio to microwave frequencies

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Topological Matter

  • proximity-induced magnetism and superconductivity on topological insulators
  • impurity resonances and topological defects in the surface state of topological insulators
  • applications of magnetically doped topological insulators to spintronics and quantum information technology

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Graphene and Graphene-based Devices

  • low-temperature PECVD growth of high-quality large-area strain-free graphene
  • nano-scale strain energineering of graphene for designer gauge potentials and novel nano-electronics
  • development of graphene-based photovoltaic cells

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Magnetism

  • physical origin and systematic control of the colossal magnetoresistive (CMR) effect in perovskite manganites
  • discovery and investigation of giant spontaneous Hall effect in perovskite cobaltites

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Instrumentation

  • a variable-temperature (from ~ 2 to 300 K) high-field-compatible scanning tunneling microscope (STM) and spin-polarized STM with both atomic-scale spatial resolution and large scanning area
  • a variable-temperature (from ~ 8 to 300 K) ultra high vacuum (UHV) scanning tunneling microscope (STM) combined a scanning electtron microscope (SEM) for efficient placement, imaging and spectroscopic studies of nano-scale structures and nano-arrays
  • a variable-temperature (from ~ 4 to 300 K) high-field-compatible UHV scanning tunneling microscope (STM) combined with a near-field scanning optical microscope (NSOM) for studies of tunneling magnetoresistance and electroluminescence of organic/magnetic heterostructures with nano-scale spatial resolution
  • broadband apparatus for small-signal complex resistivity and magnetic susceptibility measurements
  • superconducting cavity-stabilized oscillators (SCSO) integrated with the high-resolution thermometry for state-of-the-art frequency standards and for precise measurements of fundamental physical properties of quantum gases and fluids
  • high-Q dielectric microwave resonators for cryogenic surface impedance measurements of materials in high magnetic fields and over a broad frequency range

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Low-dimensional Systems

  • local electronic states of FM-filled carbon nanotubes and related nano-scale devices
  • novel electronic properties of strained silicon nano-pillars at the nano and atomic scales. (In collaboration with Professor Axel Scherer).

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Spintronics

  • Fabrication of heterostructures of organic semiconductors and ferromagnetic manganites (OSE/FM) using a pulsed laser deposition (PLD) system and an evaporation chamber
  • Investigation of the spin and charge quantum transport in the OSE/FM heterostructures using a spin-polarized STM/NSOM
  • Optimization of the OSE/FM heterostructures for best tunneling magnetoresistance and electroluminescence
  • Development of soft lithographic techniques for making spintronic & optoelectronic devices based on optimized FM/OSE/FM heterostructures
  • Engineering crossed FM-filled carbon nanotubes for nano-scale spintronic devices

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