Emergent physics in atomically thin semiconductors

by Atac Imamoglu

Thursday 10 Apr 2025, 15:15 → 16:15 Europe/Stockholm

When two atomically thin semiconductor layers are stacked with a twist, interaction between electrons become dominant over their kinetic energy. Such a system provides a fertile ground for investigation of new physics, such as magnetism with kinetic origin or quantum Hall states in the absence of a magnetic field. Such moire superlattices in two dimensional semiconductors have enabled the observation of a wealth of physical phenomena driven by strong electronic correlations, ranging from Mott-Wigner states to fractional Chern insulators. After reviewing electronic and optical properties in this new playground for condensed matter physics, I will describe two experiments. First, I will show magnetic correlations in the vicinity of a Mott-insulator state of electrons. By observing electronic magnetization through the strength of the polarization-selective attractive polaron resonances, we find that when the Mott state is doublon doped, the system exhibits ferromagnetic correlations in agreement with the Nagaoka model. Second, I will show very recent experiments demonstrating optical orientation of Chern insulator states.

About the Speaker: 

Atac İmamoğlu graduated from TED Ankara College in 1981.  He received his BSc in electrical engineering at the Middle East Technical University, and his Ph.D. from Stanford for his work on Electromagnetically Induced Transparency and Lasers without Inversion. He did post-doctoral work on atomic and molecular physics at Harvard.In 1993, he joined the Electrical and Computer Engineering Department of University of California, Santa Barbara. In 1999, he became a professor of electrical engineering and physics. In 2001 he moved to the University of Stuttgart in Germany. Since 2002, he has been working at ETHZ (Swiss Federal Institute of Technology), Switzerland, where he is heading the research group on Quantum Photonics He received the Charles Townes Award of the Optical Society of America in 2010, Quantum Electronics Award of IEEE in 2009, the Muhammed Dahleh Award of UCSB in 2006, the Wolfgang Paul Award of the Humboldt Foundation in 2002, the TÜBİTAK prize for physics in 2001, David and Lucile Packard Fellowship in 1996, and National Science Foundation Career Award in 1995.He is a member of the Scientific Advisory Committee at the IMDEA Nanoscience Institute. He is a fellow of the American Physical Society, of the Optical Society of America and the Turkish National Academy of Sciences.