Research Interests
My general research interest involves
understanding strongly correlated electron materials and developing new
analytical and numerical methods for related studies. Currently I am interested
in
Magneto
transport experiments in Si MOSFETs near the metal-insulator transition (MIT)
indicate that the non-perturbative Mott-Hubbard mechanism is responsible for
the various interesting observations. (cond-mat/0608010) I am interested in
studying the competition and interplay (1) between correlation and disorder and
(2) between the localizations due to the short-range part (Mott-Hubbard) and
the long-range tail (Wigner) of the Coulomb interaction. I am currently working on
the magneto transport and magnetic quantum oscillations near the Mott-Hubbard
transition.
By using an effective two-impurity Anderson model near half-filling, it is found that the RKKY interaction changes from antiferromagnetic in the magnetic phase to ferromagnetic in the Kondo phase. This provides a possible mechanism of producing huge magnetic entropy near the quantum phase transition. (PRL 95, 016402) Possible relations to the many other observations are of my interest, including the non-conventional superconducting phase.
To apply the dynamical mean field theory (DMFT) in realistic calculations, it is important and urgent that (1) a self-contained and reliable first-principle method be developed to derive an effective low-energy model for the correlated model, (2) the spatial correlations be handled properly via the non-local part of the self-energies, and (3) various measurables be calculated in order to compare with the experiments. Projects along these directions are currently in progress.
The behavior of electrons near the Mott-Hubbard transition is strongly influenced by external disturbances, like the electric or magnetic fields or the tortional oscillation. It is of my particular interest and also of practical importance to describe and understand the correlation-induced localization and delocalization in quasi-1D systems on a ring under these external disturbances
Multiferroics are those materials in which there are coexistence of and interplay between ferromagnetism and ferroelectricity. They show promising applications in various fileds. Understanding the underlying mechanism is crucial for the applications and material designing. However, most well-understood ferroelectric behavior requires a soft phonon mode at the zone center and can not coexist with magnetism. My focus is thus on electronic ferroelectricity. I am using exact exchange density functional code for this project.