Ph.D., 1978, California Institute of Technology
B.S., 1974, California Institute of Technology
William Barton Rogers Professor of Physics
Experimental Condensed Matter Physics
My research group currently focuses on three projects: (i) Experimental and computational study of semiconductors for thermoelectric conversion and cooling. The narrow-bandgap semiconductors studied by us are often in the proximity of topological semimetals that show unusual thermo-magnetic and electrical transport properties. (ii) Synthesis of thin films and computational study of ferrimagnetic and antiferromagnetic heterostructures that show intriguing magnetic and transport properties, e.g., skyrmionic state and anomalous Hall effect. The unique magnetic spin texture and fast dynamics are ideal for low-power and ultrafast spintronics. (iii) In our third project, we employ machine learning to locate high-entropy alloys HEAs (aka compositional complex alloys) with specific properties in the high-dimensional composition space. The enormous flexibility of HEAs offers nearly unlimited possibilities for realizing superior physical and functional properties.
1. “Amorphous Ferrimagnets: An Ideal Host for Ultra-Small Skyrmions”, S. Joseph Poon and Chung Ting Ma, J. Supercond. Novel Magnetism 33, 269 (2020).
2. “Robust Formation of Ultrasmall Room-Temperature Neél Skyrmions in Amorphous Ferrimagnets from Atomistic Simulations”, Chung Ting Ma, Yunkun Xie, Howard Sheng, Avik W. Ghosh, and S. Joseph Poon, Scientific Reports 9:9964 (2019).
3. “Half Heusler Compounds: Promising Materials for Mid-to-High Temperature Thermoelectric Conversion”, S Joseph Poon, J. Physics D: Appl. Phys. 52, 493001 (2019).
4. “Enhanced Figure of Merit in Bismuth-Antimony Fine-Grained Alloys at Cryogenic Temperatures”, Sheng Gao, John Gaskins, Xixiao Hu, Kathleen Tomko, Patrick Hopkins, and S. Joseph Poon, Scientific Reports, 9:14892 (2019).
5. “Multi-Principal-Element Approach to High-Performance Thermoelectric Materials”, S. Joseph Poon and Jian He, book chapter in Encyclopedia Mater. Sci. edit. Michael Gao (Elsevier, 2019). https://www.sciencedirect.com/science/article/pii/B9780128035818117199.6. “High Entropy Alloys Mined from Phase Diagrams”, Jie Qi, Andrew M. Cheung, and S. Joseph Poon, Scientific Reports, 9:15501 (2019).