CAREER: Nonequilibrium Dynamics of Spin-Correlated Excitons in van der Waals Magnets

Nontechnical Abstract:

Two-dimensional materials are transforming science and technology by offering exceptional physical properties not found in bulk solids. Among these, semiconducting van der Waals magnets provide unique opportunities to study and manipulate optical and magnetic phenomena. When exposed to light, these materials generate excitons—bound pairs of an electron and a positively charged hole that transport energy across the crystal.

Unlike conventional excitons, those in van der Waals magnets are deeply influenced by the material’s intrinsic magnetism, enabling novel functionalities. This project examines the properties of these exotic particles, exploring their microscopic interactions and developing control strategies to achieve long-range energy transport with minimal dissipation.

By employing advanced optical techniques and tailored laser pulses, this research contributes to the emerging field of 'magneto-excitonics,' where the synergistic interplay of magnetic and optical properties enables innovative applications in quantum devices, energy-efficient nanophotonics, and information processing. Complementing these research efforts, the project addresses critical challenges in STEM education, inspiring and preparing the next generation of scientists and engineers.

The activities engage over 30 undergraduate students and 50 K-12 educators in advanced research, fostering a pipeline of STEM professionals and cultivating sustained interest in science and technology from an early age. Strategic partnerships with Austin’s semiconductor industry ecosystem support a mentorship program impacting over 150 undergraduate students, offering valuable networking opportunities with role-model leaders and equipping participants with the knowledge and skills essential for success in the high-tech sector.

These initiatives strengthen retention in STEM fields, contribute to workforce development, and bridge the gap between academia and the local semiconductor industry. Technical Abstract:

Semiconducting van der Waals magnets host various classes of strongly bound excitons closely tied to the underlying spin order, showing exotic magneto-optical phenomena and high sensitivity to external stimuli. Unveiling methods to manipulate these spin-correlated excitons on ultrafast timescales is a critical goal in van der Waals materials research.

Theoretical frameworks suggest that exciton properties can be dynamically tailored by engineering the magnetic or crystallographic environment out of equilibrium, and preliminary spectroscopic observations indicate that certain exciton species may exhibit coherent (i.e., wavelike) propagation over tens of picoseconds. The primary goal of this project is to gain a profound understanding of spin-correlated excitons in semiconducting van der Waals magnets by revealing their interactions with low-energy collective modes (e.g., phonons, magnons) and clarifying how exciton creation influences the underlying magnetic order.

Building on these insights, the Principal Investigator aims to map the spatiotemporal propagation of these bound species and develop cutting-edge protocols—based on coherently evolving magnetic/crystal environments or optical microcavities—to enhance exciton coherence over macroscopic length scales. This research is integrated with a series of educational and outreach activities.

Collaborations with UT Austin’s NSF Materials Research Science and Engineering Center and the Texas Institute for Electronics provide undergraduate students with hands-on research opportunities and connect them to Austin’s thriving semiconductor industry ecosystem through a dedicated mentorship program. The project also engages K-12 educators by offering workshops that introduce groundbreaking scientific discoveries and equip them with innovative teaching strategies to inspire the next generation of STEM leaders.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.