Seminar & Colloquium
[세미나: 7월 8일(월), 오전 10시] Dr. Kisung Kang, Fritz Haber Institute of the Max Planck Society, Germany
Title
Unraveling Electron-Lattice-Magnetism Interactions: First-Principles and Machine Learning Studies
Speaker
Dr. Kisung Kang, Fritz Haber Institute of the Max Planck Society, Germany
* Education
- 2016.08. ~ 2022.05. Ph. D. in Materials Science and Engineering, University of Illinois at Urbana-Champaign, IL, USA
- 2009.03. ~ 2015.02. B.S. in Materials Science and Engineering, Yonsei University, Republic of Korea
* Professional Experience
- 2023.12. ~ present Group Leader, The NOMAD laboratory, Fritz Haber Institute of the Max Planck Society, Germany
- 2022.04. ~ 2023.12. Postdoctoral Researcher, The NOMAD laboratory, Fritz Haber Institute of the Max Planck Society, Germany
| Date | Monday, July 8th , 2024
| Time | 10:00 ~
| Venue | 33동 222호(동부 세미나실)
[Abstract]
Electrons, lattice, and magnetism are intricately intertwined as the fundamental components of materials. Their excitations and interactions are crucial to understanding materials’ properties, such as temperature-dependent transport phenomena and optical spectra. The complexity of their interaction offers new functionalities of materials but also sets back a comprehensive understanding of the physical origin of material phenomena. For non-magnetic materials, the excitation and interaction of electrons and lattice deeply influence their properties. In magnetic materials, magnetism comparably (or sometimes dominantly) contributes to the property and, in addition, provides new functionalities like magneto-optical effects. To disentangle their complicated interactions, computational approaches have recently paved another way to analyze the materials' ground and excited state properties by manipulating electrons, lattice, magnetism, and their couplings. This talk first addresses the electron-lattice interaction, exemplified by the transport properties of thermoelectric materials. The non-perturbative method using first-principles approaches explicitly describes lattice dynamics at finite temperature and addresses strongly anharmonic behavior, which induces low thermal conductivity. Although its usage has been constrained due to the high computational cost, machine learning tools have recently complemented the first-principles approaches, accelerated transport property calculations, and effectively explored thermoelectric material space. The second part of the talk introduces a novel approach for electron-lattice-magnetism interactions based on expanding the non-perturbative method into magnetic materials. This approach can describe both lattice and spin dynamics in the magnetic material at finite temperatures and can control individual electron, lattice, and magnetic temperatures. The calculated (magneto-)optical spectra of ferromagnetic BCC Fe demonstrate that the new method can capture temperature-dependent phenomena and simultaneous electron-lattice-magnetism coupling effects. The expanded non-perturbative approach is expected to be utilized in confronting questions about the physical origins of material phenomena in electronics and spintronics.
| Host | 장혜진 교수(02-880-7096)