Colloquium: Probing spectroscopic landscape of low-dimensional quantum materials: A first-principles perspective

ABSTRACT

The exploration of low-dimensional quantum materials has unveiled unprecedented opportunities for next-generation electronic devices. To fully harness their potential, it is essential to delve into the intricate details of their electronic and optical properties. Spectroscopy, by probing the response of materials to those perturbations, allows the analysis of the induced elementary excitations and hence the characterization of the material properties. Theoretically, the many-body quantum theory with quantitative calculations can explain the origin and make the predictions of experimental spectroscopy. Indeed, recent breakthroughs in the emergent low-dimensional quantum materials thanks to the paradigm of collaboration between modern electronic structure theories and advanced experimental techniques.

Beyond mean-field models of independent electrons, such as density functional theory (DFT), we performed the density functional perturbation theory (DFPT) and/or GW+BSE calculations within the many-body perturbation theory (MBPT) to tackle following interesting and novel phenomena of low-dimensional quantum materials:

1. In-plane anisotropy of layered compounds SnS1-xSex.

2. Dimensionality crossover of charge-density-wave (CDW) in CuTe.

3. 2D ferroelectricity of vertical heterostructure of h-BN layers and graphene substrate.

In an excellent agreement with recently available experiments, our calculated spectra not only provide insights into underlying mechanisms of electronic excitations but also pave a path to rational design of materials for novel optoelectronic applications.

BIOGRAPHY

Prof. Hung-Chung Hsueh received his Ph.D. in Physics from University of Edinburgh at Scotland, UK in 1997/01. He joined the Department of Physics at Tamkang University, Taiwan, in 1997/08. He conducted as the Chairman of the Department of Physics during 2018-2022. Also, he was the Chairman of the Bachelor Program in Advanced Materials Science during 2019-2022. He is currently the Dean of the Office of Research and Development and the professor of the Department of Physics at Tamkang University. His research focuses on explaining and predicting the unique properties of novel nano/quantum materials using first-principles simulations.