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Postdoctoral Scholars

Dr. Laura Chaix

I joined the Shen group on January 2015 as a postdoctoral researcher. I received my Ph. D. degree from the University of Grenoble (Joseph Fourier University) in France. My research activities were performed in collaboration between the Institut Néel, CNRS France and the Institut Laue-Langevin. During my thesis, I worked on the dynamical magneto-electric coupling in multiferroic compounds using two complementary experimental techniques: unpolarized and polarized neutron scattering and THz spectroscopy. My current research interest is on the study of dynamical structural, magnetic, and electronic properties of strongly correlated systems using resonant x-ray diffraction (RXD) and resonant inelastic x-ray scattering (RIXS). I also focus on the time-­resolved RXD and RIXS capabilities at the x-ray free electron laser facility LCLS (Linac Coherent Light Source).
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Dr. Yongtao Cui

I joined Shen Group as a postdoc fellow in September 2011. I received my Ph.D. degree in Applied Physics from Cornell University. My Ph.D. work was focused on the studies of magnetic dynamics in a nano-magnet excited by transfer of the spin angular momentum from itinerant electrons. I am now working on the Microwave Impedance Microscopy (MIM) technique - using it to probe materials' dielectric properties at the nano-scale, and expanding its capacity to study even richer physics.
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Dr. Junfeng He

I joined Shen Group as a postdoctoral research fellow in October 2015. I received my Ph.D from the Institute of Physics, Chinese Academy of Sciences in 2013. From 2013 to 2015 I was a postdoctoral researcher at Boston College. For my thesis I studied the electronic structures of Cuprates and FeSe/STO films using angle-resolved photoemission spectroscopy (ARPES). My current research interest is on the study of electron doped cuprates and iridates.
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Dr. Heike Pfau

In October 2015, I joint the Shen group as a postdoctoral research fellow supported by a Feodor Lynen Fellowship from the Humboldt Foundation in Germany. I received my Ph.D in March 2015 from the TU Dresden, Germany. In my thesis work conducted at the Max-Planck Institute for Chemical Physics of Solids (MPI CPfS), I studied heavy fermion systems focusing on quantum criticality, the Kondo effect, and Lifshitz transitions. Additionally, I studied a skutterudite compound to reveal its superconducting order parameter. Technically, I concentrated on thermal and thermoelectric transport at very low temperatures. Here, I am utilizing the facilities provided by the Stanford University and the Stanford Synchrotron Radiation Lightsource (SSRL) to study Iron-based high-temperature superconductors by means of angle-resolved photoemission spectroscopy in order to investigate their unconventional superconducting nature. It is fascinating for me to explore unconventional electronic phases in strongly correlated electron systems using different experimental techniques: traditional low-temperature bulk probes and modern spectroscopy.
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Dr. Jonathan Sobota

I received my B.S. from Cornell University in 2007 and my Ph.D. from the Shen group at Stanford University in 2014. I am now continuing as a postdoc with a joint affiliation at Lawrence Berkeley National Lab. For my thesis I studied electron and lattice dynamics in topological insulators using ultrafast photoemission spectroscopy. However, these experiments were blind to the electron spin, which is a central property of these materials. For my postdoctoral work I will overcome this limitation by implementing a novel photoelectron spin detector. This will allow me to study spin structure and dynamics in topological insulators, as well as magnetic materials and strongly coupled electron systems.
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Dr. Hafiz Muhammad Sohail

I joined Shen group in Sept. 2015 as a postdoctoral researcher. I received my PhD degree in surface and semiconductor physics, in April 2014 from Linköping University, Linköping, Sweden. After that I continued as a postdoctoral researcher until Aug. 2015 within the same group. During last six years, I studied various metal and elemental semiconductor surfaces either clean or modified with adsorbates. These surfaces together with adsorbates reconstruct into new two dimensional structures which have periodicities bigger than that of bulk terminated surface. The experimental techniques used to characterize these surfaces were LEED, core level spectroscopy, ARPES and STM. In some cases, atomic models and electronic band structures were investigated by density functional theory (DFT) calculations. The APRES studies were performed at the MAX IV synchrotron radiation facility in Lund, Sweden. Currently, in Shen group, I am interested in the study of strongly correlated electrons systems such as cuprate superconductors and topological insulators. I will mainly utilize high resolution ARPES and or spin-ARPES techniques to unveil exotic properties of these systems. In Shen group, my research will be supported by Knut and Alice Wallenberg foundation, Sweden.
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Dr. Hadas Soifer

I joined the Shen group as a postdoctoral researcher in November 2014. I received my Ph.D from the Weizmann Institute of Science in Israel. My Ph.D. research was in the field of attosecond physics – I studied structure and extremely fast dynamics of electrons in atoms and molecules, through the strong-light matter interaction known as High Harmonics Generation. Here I work on time-resolved ARPES experiments on quantum materials. I am fascinated by the complex interactions between the different degrees of freedom in these materials, and by the potential to probe and control these interactions with light.
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Dr. Hao Yan

I am currently a joint postdoctoral fellow between Shen and Melosh labs. I received my Ph.D. in chemistry from Harvard in 2010. From 2010 to 2011 I was a postdoctoral researcher at Harvard under the advisory of Charles Lieber. My current research focuses on the material science of diamondoids - essentially molecular-scale diamond. Our unique capability to separate, chemically functionalize and assemble these molecules offers an ideal playground for materials scientists to study the properties of diamond and diamond-like structures at the nanometer scale. My current interest lies on the photoemission and electron-phonon interaction in diamondoids and their hybrid structures; in the long term I am also interested in understanding their thermal, mechanical and electronic properties, as well as their applications.
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Dr. Chaofan Zhang

I am currently a postdoctoral fellow in Shen Group with the support from the Wallenberg Foundation in Sweden. I received my Ph.D. in cluster physics from Uppsala University and most works in that period were done at Swedish synchrotron radiation facility MAX IV laboratory. There I studied the gas-phased materials, mainly the atmospheric nano-particles, using the x-ray photoelectron spectroscopy (XPS). My current research interest is to study at an atomic scale the strongly-correlated electron materials in momentum space via high resolution ARPES experiments. I would like to unveil the many-body interactions in the ultra thin film grown by the molecular beam epitaxy (MBE) technique. By studying the phenomenology and understanding the underlying principles, I hope to discover the many potential applications of thin film physics.
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