Title:Phase transition in materials for energy-efficient computing and ultra-sensitive sensors
Speaker:Junwoo Son,Seoul National University (SNU)
Time:2024-10-15 15：00pm
Venue: C302,New Science Building
Abstract:The discovery of quantum materials featuring metal-insulator transition (MIT) has prompted efforts to control and exploit the phase transition by applying external stimuli (e.g., temperature, strain, defects, voltage). Due to extreme sensitivity and low-energy reversible switching near phase boundaries in emerging phase-transforming materials, small changes in the external stimuli can trigger significant modulation in physical properties. For example, as an archetypical quantum material with an MIT, VO2 undergoes abrupt MIT upon more than four orders of magnitude of electrical-conductance modulation, along with nanosecond transition time. These sensitive and abrupt transitions assisted by strong electron-lattice coupling have made phase-transforming materials candidates for energy-efficient computing and ultra[1]sensitive sensors. In this presentation, I will present my research efforts to demonstrate the reversible and percolative control of phase transition by external stimuli for unprecedentedly sensitive sensors and energy-efficient computing. First, our strategy for hydrogen-driven phase transition in VO2 will be introduced to dramatically change electrical resistance without disrupting the lattice framework [1], which can be applicable for the femto-mole-sensitive and biomarker-specific sensing of neurotransmitters in the brain [2]. Furthermore, I will discuss the new concept of zero-strain metal-insulator transition with nanoscale structural heterogeneity by doping to eliminate geometric incompatibility and decouple structural phase transition during electronic phase transition for robust switching [3]. [1] H. Yoon et al., Nature Materials 15, 1113 (2016) [2] J. Kim et al., (in revision) [3] Y. Park et al., (submitted）
Bio:Junwoo Son is an Associate Professor of Materials Science and Engineering at Seoul National University (SNU). He received his BS in Materials Science and Engineering from Seoul National University (2005) and his PhD in Materials from the University of California, Santa Barbara (2011). Before joining SNU in 2024, he was an assistant and associate professor at POSTECH (2013 ~ 2024). He is also affiliated with the Research Institute of Advanced Materials and the Institute of Applied Physics at SNU. He serves as a Review Board member of the National Research Foundation of Korea and a committee member of the Korean Association for Industrial Technology Security. His research interests include 1) understanding of the structure-property relationship of nanoscale oxide thin films and heterostructures, including strongly correlated materials, oxide semiconductors, and low-dimensional oxides, and 2) design of new functionality for electronic applications. Prof. Son has authored or co[1]authored more than 90 peer-reviewed publications, including Nature Materials, Nature Electronics, Nature Communications, Advanced Materials etc.
