Primary Research Activities

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

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

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

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

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

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).

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