Hot Topics In Ultrafast: Terahertz Field Induced Metastable Magnetization in a Van Der Waals Antiferromagnet

Join the Optica Ultrafast Optical Phenomena Technical Group for this special hot topic session featuring Professor Nuh Gedik from Massachusetts Institute of Technology. The session will start with Professor Gedik giving a talk on terahertz field induced metastable magnetization in a van der waals antiferromagnet, which will be followed by a panel discussion on the topic.

Controlling the functional properties of quantum materials with light has emerged as a frontier of condensed matter physics, leading to discoveries of various light-induced phases of matter, such as superconductivity, ferroelectricity, magnetism, and charge density waves. However, in most cases, the photoinduced phases return to equilibrium on ultrafast timescales after the light is turned off, limiting their practical applications. 

Prof. Gedik uses intense terahertz pulses to induce a metastable magnetization with a remarkably long lifetime of over 2.5 milliseconds in a van der Waals antiferromagnet, FePS3. The metastable state becomes increasingly robust as the temperature approaches the transition point, suggesting a significant role played by critical fluctuations in facilitating extended lifetimes. By combining first principles calculations with classical Monte Carlo and spin dynamics simulations, he finds that the displacement of a specific phonon mode modulates the exchange couplings in a manner that favors a ground state with finite magnetization close to the Néel temperature. This analysis also clarifies how critical fluctuations amplify the magnitude and the lifetime of the new magnetic state. This discovery demonstrates the efficient manipulation of the magnetic ground state in layered magnets through non-thermal pathways using terahertz light, and establishes the regions near critical points with enhanced fluctuations as promising areas to search for metastable states.

Subject Matter Level: Intermediate - Assumes basic knowledge of the topic

What You Will Learn in the Webinar:
• Discovery of a new magnetic state that can be studied and manipulated on ultrafast pulses toward creating new quantum material phases and metastable states
• Listen to our discussion panel on future directions for magnetic and phase change quantum materials

Who Should Attend the Webinar:
• Students and researchers in condensed matter and terahertz ultrafast physics
• Technical group members from other ultrafast disciplines interested in a hot topics emerging ultrafast area of magnetic quantum materials

About the Presenter: Nuh Gedik from Massachusetts Institute of Technology

Professor Gedik joined MIT Physics Department as an assistant professor in January 2008. He received his B.S. in Physics in 1998 from Bogazici University, Istanbul, Turkey and his Ph.D. in Physics in 2004 from University of California, Berkeley. After his Ph.D., he moved to Caltech where he worked as a postdoctoral scholar till January 2008. His awards include National Science Foundation CAREER Award, Department of Energy Early Career Award, Sloan fellowship, DARPA Young Faculty Award and Moore Experimental Investigator award. He was promoted to Full Professor of Physics in 2018.