MAE Seminar: Principles of Solid-State Heat-to-Electricity Conversion Based on Spin

McDonnell Douglas Engineering Auditorium (MDEA)
Joseph P. Heremans
Ohio Eminent Scholar, Mechanical & Aerospace Engineering
Ohio State University
Abstract: Solid-state heat conversion provides practical cooling at low power levels and has the potential to recover waste heat at low power levels (<1kW). The efficiency of thermoelectric materials improved by about a factor of two over 20 years, a result obtained mostly by reductions in lattice thermal conductivity. This is now near the amorphous limit; further improvements require new ideas. The newly discovered spin Seebeck (SSE) effect opens a new path to solid-state energy conversion: the concepts of thermal spin transport add new approaches to the classical research on thermoelectrics. This talk will explain what SSE, an advective transport process, is. The temperature gradient pushes a magnon flux in a ferromagnet; this interacts with conduction electrons in an adjacent layer to produce an electric field. In more practical embodiments, the physics can be integrated inside bulk ferromagnetic metallic alloys and in nanocomposites.
Bio: Heremans is an Ohio Eminent Scholar and professor in the Mechanical and Aerospace Engineering Department at Ohio State University, with appointments in the Materials Science and Engineering Department and the Department of Physics. He is a member of the National Academy of Engineering and a fellow of the AAAS and the American Physical Society. He joined OSU after a 21-year career in the automotive industry at General Motors Research Laboratories, where he was the section manager for Semiconductor Physics, and at the Delphi Research Laboratories. His research interests focus on energy conservation and recovery and lie at the intersection between experimental condensed matter physics and thermodynamics. In the last decade, he worked on the transport of heat, charge and magnetization in solids. For example, the articles pertaining to the talk above include: Jaworski ... JPH, Nature Materials 9 898 (2010); Jaworski … JPH, Nature 487 210 (2012); JPH & al, Nature Nanotechnology 8 471 (2013); Jin … JPH, Nature Materials 14, 601 (2015); Boona … JPH, Nature Communications, accepted (2016).