Physics on a Camelback: The Wonder and Applications of a Parallel Dipole Line System - A Novel Magnetic Trap and High Sensitivity Hall System
Wednesday, March 25, 2015 - 1:00pm to 3:30pm
Dr. Oki Gunawan - IBM T.J. Watson Research Center
I present a discovery of new context, where a one-dimensional "camelback" potential occurs, arising from elementary field sources—i.e. in a "parallel dipole line" (PDL) system. This system can be realized with a pair of cylindrical magnets with diametrical magnetization. The camelback potential leads to several interesting applications: it enables a unique trap for cylindrical objects, produces a 1-D mechanical oscillator with tunable Q-factor and a system to measure the magnetic susceptibility of the trapped object. The PDL system also yields a surprising application for a high sensitivity Hall measurement using a rotating “master-slave” PDL configuration. This system played a decisive role in extracting low carrier mobility values in earth-abundant kesterite solar cells and in monitoring carrier density in perovskite solar cells; both are materials of high interest in photovoltaics. I will also discuss further exciting applications of the PDL system and its fascinating 1-D camelback potential.
Oki Gunawan received his PhD from the Dept. of Electrical Engineering, Princeton University and his M. Eng and B. Eng from Nanyang Technological University, Singapore. He is currently a Research Staff Member in the Photovoltaics Science and Technology Department at the IBM Thomas J Watson Research Center, Yorktown Heights NY. His research activities encompass several areas such as optoelectronics, valley-based electronics or “valleytronics”, nanowire devices, photovoltaics characterization and currently earth abundant CZTSSe solar cells. At IBM, he led efforts to develop a portfolio of new instruments, systems and patents for advanced solar cell characterizations. His works have been published, in among other journals, Nature Physics, Physical Review Letters, Physical Review B, Nano Letters, Applied Physics Letters and Progress in Photovoltaics. He currently holds 6 US patents, with 12 pending.