(Apr. 13) 76th Academic Lunch Seminar of Sino-French Institute of Nuclear Engineering and Technology
Last updated :2018-04-09
Topic: Microscopic piezoelectric and thermoelectric theories and their new applications
Speaker: Dr. Yunhua WANG
Time: 12:40–14:00, Friday, April 13, 2018
Venue: F309 in the teaching building, Zhuhai Campus, SYSU
Organizer: Sino-French Institute of Nuclear Engineering and Technology, Sun Yat-sen University
Since its first observation in 1880 by Curie brothers, piezoelectricity has attracted considerable attention in physics, materials and engineering, because of its interesting fundamental theory and wide applications in diverse fields. It was not until 1994 a breakthrough on the piezoelectric physics was made by linking the geometric phase with the density functional theory (DFT), where the piezoelectric coefficients measuring the bulk piezoelectricity can be calculated numerically. As we know that, the resistance (R) of a bulk metal or a semiconductor has a concise formulation with corresponding physical meanings, e. g., R=ρL?S, for a cylindrical wire. Similar formulations are quite useful to directly assess the physical properties of a bulk material and design new materials. A natural question arises: whether there are also concise formulations for piezoelectricity. In this talk, I will introduce our recent works to address this problem and also present some applications of the constructed microscopic piezoelectric theory.
The thermoelectric effect usually encompasses the Seebeck effect, Peltier effect, and Thomson effect, which were discovered more than 100 years ago. Owing to the simple and robust conversions of temperature differences to electric voltage and vice versa, the thermoelectric effect has versatile applications in thermal engineering and electronics. Recently, the microscopic interplay among the thermoelectricity, spintronics and valleytronics has opened another door to explore the thermoelectric properties in new material systems and design nanostructures with high thermoelectric performance. In this talk, I will also introduce our recent works on thermoelectric behaviors of the Dirac (Weyl) materials with high spin or pseudospin degrees of freedom.
About the speaker:
Yunhua WANG got his Ph.D. degree in Condensed Matter Physics from Sun Yat-sen University in 2014. His recent research interest includes microscopic piezoelectric and thermoelectric theories, optoelectronic and thermoelectric calculations for quantum materials and couplings between the elastic field and quantum phase.