Research
Our current research focuses on the following general directions:
- Strongly correlated electronic systems, including competing orders in
superconducting and magnetic perovskite oxides, pairing mechanism of cuprate
superconductors, and Luttinger liquid behavior in DNA-templated metallic nanowires
- Nano-scale instrumentation with variable temperature capabilities for
surface and subsurface characterizations of the electronic and mechanical
properties of novel nanostructures, nano-assemblies and molecules
- Organic/Magnetic Heterostructures for Spintronics & Optoelectronics
- Investigation of spin and charge quantum transport in the heterostructures using
cryogenic STM/SNOM
- Optimizing the tunneling magnetoresistance and electroluminescence for spintronic and optoelectronic applications
- Applications of Superconducting Cavity Stabilized Oscillators
- Precise measurements of the Bose-Einstein condensation of quantum gases
and critical phenomena of quantum fluids
- High frequency stability microwave sources
Our primary research activities in the past few years have concentrated on the
following areas:
- Superconductivity:
- competing orders and pairing symmetry/mechanism of cuprate superconductivity
- 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
- pairing potential and pairing symmetry of a new superconductor MgB2
- 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
- Instrumentation:
- high-Q dielectric microwave resonators for cryogenic surface impedance measurements of
materials in high magnetic fields and over a broad frequency range
- 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
- a variable-temperature (from ~ 2 to 300 K) high-field-compatible scanning tunneling microscope
(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
- Nano-electronics:
- investigation of atomically resolved electronic density of states of graphene and graphene-based nano-electronic
devices as a function of temperature and magnetic fields (in collaboration with Professor Marc Bockrath in Applied Physics)
- investigation of the local electronic states of metal-filled carbon nanotubes and related nano-scale devices
(in collaboration with Professor Marc Bockrath in Applied Physics)
- 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