1.New materials of superconductor

2.Pairing mechanism of superconductors

3.Flux dynamics

4.New phenomena in Mott insulator

Academic Contributions

i. In collaboration with Prof. R. Griessen's group, invented the Generalized Inversion Scheme for calculating the intrinsic critical current density and pinning energy. Discovered different pinning mechanisms(Tc fluctuation or mean free path fluctuation) of vortices in high temperature superconductor bulk samples and thin film samples;

ii. Discovered the magnetic field induced dimensional transition of vortex system in Tl-2212 system, and the zero temperature vortex glass melting at a high magnetic field;

iii. Measured the upper critical magnetic field of overdoped high temperature superconductors and concluded that there is no extremely positively curved Hc2(T) anomaly and clarified this heavily debated issue;

iv. Investigated many properties of the flux dynamics of the MgB2 system, found the small dense flux avalanches in MgB2 thin films, and among the very early groups pointed out the non-isotropic s-wave pairing symmetry;

v. Investigated the low energy excitations in many systems, include copper oxide superconductors, sodium doped cobalt oxide, CDW materials.