Research in the Gweon Group

Electron spectroscopy on novel emergent materials

What do condensed matter physicists confront day in and day out? It is electrons -- a lot of electrons. Due the their sheer large number, these electrons show emergent properties that are not inherent when electrons are individual particles. The single particle spectroscopy in Gweon's group is one of the major techniques to probe these emergent properties. Different emergent states, e.g. Fermi liquid states (gray) and non-Fermi liquid states (red), show completely different finger-prints in the single particle (read "electron") spectroscopy.

The past half century might be called a Si era, in the sense that the Si industry changed our world. In condensed matter physics, it was an era that the celebrated Fermi liquid theory, in which a system of interacting electrons can be mapped to a system of non-interacting electron-like quantum excitations (i.e. Landau quasi-particles), provided a bedrock principle on which to build textbook condensed matter physics principles, which are essential to understand materials such as Si.

However, there is a widespread realization now that the paradigm of the Fermi liquid theory is only one type of theory. New states can emerge from electrons, and the properties of a new state may not have any resemblance to the properties of non-interacting electrons. The emergence of these new states of matter seems closely related to competing phases such as those found in novel materials including high temperature superconductors, colossal magneto-resistant materials, and rare earth inter-metallic materials. Understanding these new states are undoubtedly the central task for contemporary condensed matter physicists. In the Gweon group, research is focused on emergent properties of important materials such as high temperature superconductors, two leg ladder compounds, cobalt oxides, and graphene.

The main technique used in the Gweon group is the so-called angle resolved photoemission spectroscopy (ARPES). G.-H. Gweon's Ph. D. thesis may be of interest to people wanting to know more about ARPES. The thesis is available as a pdf file, in 4 different formats: double-sided US letter, single-sided US letter, doubled-sided A4, and single-sided A4.

To read more about research in the Gweon group, it is a good start to check out a few of G.-H. Gweon's papers available at the pre-print server (arXiv.org).

This site, especially this part, is under construction. So check again soon!