[BRK/ECE/PHYS Seminar,March 24, 2016 @ 10:40am WANG 1004 ,Dr. Yongtao Cui Postdoc Fellow, Stanford University Title: Visualizing Magnetic and Electrical Phenomena in Nano Devices in Time and Space Domains] [Abstract: Current CMOS technology is approaching the scaling limit as set by the semiconductor physics. Exploring new materials as well as other physical interactions than the electron charge, thus provides opportunities to enable new device schemes and architectures with improved performance. In the course of such study, developing new characterization techniques plays an important role to achieve better understandings in device physics and identify new functionalities. In this talk, I will discuss two case studies in probing the magnetic and electrical properties in nano devices in both time and space domains. In the first part, I will present the study of the magnetic dynamics in spin torque devices where spin polarized electrons are used to efficiently manipulate the magnetic devices, such as inducing magnetic switching or precession. We developed single-shot time domain techniques to capture the ultrafast switching processes with unprecedented details. Furthermore, X-ray microscopy measurement is performed to resolve spatially and temporally the magnetic dynamics in a ferromagnetic nanopillar, revealing the structure of the magnetic normal modes excited by spin torque. In the second part, I will introduce a new type of interface conduction at the magnetic domain walls in a magnetic insulator with strong spin-orbit coupling, Nd2Ir2O7. We used Microwave Impedance Microscopy, a scanning probe microscopy technique capable of imaging nanoscale electrical conductivity, to identify such conductive states and perform comprehensive study of its behaviors. We propose that such feature can be potentially used to achieve memory device applications beyond current CMOS scaling barrier.] [Bio: Yongtao Cui received his BS in physics from Peking University in 2005, and his PhD in applied physics from Cornell University in 2011. Since then he has been working as a postdoc in Stanford University. He has been interested in developing new characterization techniques to study device and material physics based on magnetic and electronic materials.]
