Research Interest

Research Interest

Spectroscopic Study of 2D materials

If I were to pick one of the most distinguishable things in extended structure from other phases, I would choose translation symmetry. It all begins from this symmetry, extending molecular orbitals to band structure. That simple thing endows complexity to the material; electronic band structure, long-range quantum effects, lots of coupled or competing interactions, and so forth.

2D materials, due to its low-dimensionality, have novel properties distinguished from 3D materials. For example, Van der Waals interaction of twisted graphene layers results in emergence of superconductivity. Bravais lattice vectors only need two unique vectors and correspondingly reciprocal space requires the same number. 2D crystalline symmetry shapes the Brillouin zone in the reciprocal space such that two distinguishable special points in Brillouin zone respond to electromagnetic field differently (valley polarization). Absence of z-axis in unit cell means the absence of surface state but the presence of quantum confinement effect. Evidently, low-dimensionality leads us to interesting physics that couldn't be observed in three-dimensional materials. Understanding such platform appeals its necessity as modern devices are going to ever shorter pitch width. In addition to it, many devices are based on making interfacial heterostructure and tuning properties by doping and perturbations which are sources of novel physical phenomena as well.

Photoelectron spectroscopy elucidates the structure and dynamics of electrons in its own way. Angle-resolved PES maps out electronic band structure which is fundamental element in condensed matter. Time-resolved PES captures electron dynamics and their interaction with other degrees of freedom such as lattice, spin, and orbital. Also, PES is highly depth and surface sensitive thus it is best at studying quantum statistics and dynamics in 2D materials.

During my doctorate study, I plan to study 2D materials manipulated by doping and external parameters, using spectroscopic techniques in general. To the end, I’ll try to elucidate the physics with spectroscopist perspective, broaden our understanding of 2D materials and the solid-state physical chemistry.