Optical Detection of Transverse Spin-Seebeck Effect in Permalloy Film Using Sagnac Interferometer Microscopy
Prof. Dali Sun
Department of Physics
NC State University
Abstract: Macroscopic spatially spin distribution caused by the application of an in-plane thermal gradient in a conducting ferromagnetic film, known as transverse spin-Seebeck effect (TSSE), is in many cases overshadowed by thermoelectric and magneto-thermoelectric effects when using the conventional electrical detection via the inverse spin Hall effect. Here we report an optical method for the detection and characterization of TSSE response in permalloy films using magneto-optical Kerr effect with an ultrasensitive fiber-optic Sagnac interferometer microscope that is free of magneto-thermoelectric artefacts, which also allows measurements with field direction parallel and perpendicular to the film surface. We found a substantial anisotropy in the permalloy TSSE coefficient, where the ‘in-plane magnetization’ coefficient is much larger than that in the ‘out-of-plane magnetization’. Our work paves the way for spin Caloritronics in organic-based ferromagnet.
Figure: Schematic illustration of the Sagnac Interferometer microscope for transverse spin-Seebeck measurement in a permalloy ferromagnetic film.
Biography:Dr. Sun received his PhD in 2009 from the Institute of Physics, Chinese Academy of Science, Beijing. He did postdoctoral research at Oak Ridge National Laboratory from 2009 to 2011 and at the University of Utah from 2012 to 2014. He continued to work at the University of Utah as a research assistant professor from 2015 to 2016. He recently joined the NC State Department of Physics as an assistant professor.
Dr. Sun’s research interests are in spintronics and optoelectronics of organic semiconductors, magnetic thin films and organic-inorganic hybrid perovskites. It includes the studies of organic spin valves, organic light-emitting diodes, hybrid perovskite optoelectronic/spintronics devices, and their device physics. The Sun Research Group at NC State focuses on exploring novel routes for spin injection and detection, magnetic field effect, spin Hall effect and their applications in molecules, polymers and newly emerged materials.
Date: 05/9/2017 (Tuesday)
Time: 11:00 AM
Venue: Toxicology Auditorium 2104