Personnel 

My interest on experimental condensed matter physics is to study the highly correlated electronic systems by means of photoemission spectroscopy. My current research activities include the following aspects: Academically, I’m investigating a multi-layer high-T_c superconductor family (Ba₂Ca₃Cu₄O₈(O_xF_1-x)₂) that exhibits exotic electronic properties against the common sense and a heavy fermion compound (URu₂Si₂) that exists a hidden order state in low temperature (<17.5K). Technologically, I’m developing our novel time- and spin-resolved photoemission spectrometer, which will not only give us the capability to detect the spin of electrons (which is crucial to study magnetic materials), but also extend our study from equilibrium state to electron dynamics.

I'm a postdoctoral fellow in Prof. Z.X. Shen's group. My current research interest is to understand electronic properties of strongly correlated materials especially high temperature superconductors. Current focuses is the ARPES measurements on detailed temperature dependence of the pseudogap and superconducting gap in different doping levels and materials. Before joining Shen group in April 2008, I did my Ph.D.work at the University of Tokyo. My Ph.D. thesis mainly focuses on the doping evolution of the electronic structure of the single-layer cuprates (Bi2201 and LSCO) using photoemission spectroscopy.

I am currently a postdoctoral fellow in Prof. Z.X. Shen!/s group. I spent four years in Tsinghua University for my BS degree, and five years in Princeton University for my PhD degree, both in Electrical Engineering. My Ph.D. thesis focuses on the quantum transport in high mobility Si/SiGe 2D systems under intense magnetic fields and ultra-low temperatures. I also did experiments on cyclotron resonance at microwave frequencies in GaAs 2D hole systems. My current interest is to develop a new imaging technique, known as the near-field scanning microwave microscope. With the new configuration and tip design, local dielectric constant and conductivity can be imaged at an unprecedented high spatial resolution. Such technique is expected to provide important information on the physical properties of complex materials.

I am interested in learning the underlying physics of strongly correlated materials through spectroscopic tools, which normally reveal lots of microscopic information of the electronic states. As an extension of my Ph. D. thesis work, I continue to explore the physics of high-Tc cuprates using the ultra-high resolution angle-resolved photoemission spectroscopy. The much improved resolution not only could lead to new discoveries, but also make possible a more quantitative analysis of the ARPES data. The other very exciting project I am working on is to explore the possibility of using the LCLS to do optical pump and X-ray probe experiments. New insight could be revealed via studying how the electronic state relaxes from an excited state back to the ground state.

My research interest is to understand electronic properties of strongly correlated materials such as transition metal oxides and heavy fermion systems, using various spectroscopic tools such as photoemission, x-ray absorption and inelastic x-ray scattering. Current focus is the ARPES measurements of spectral changes across phase boundaries and novel ground states in the vicinity of quantum critical points. Before joining Shen group in September 2006, I did my Ph. D. work at the University of Michigan. The main focus of my thesis is to investigate Mott-Hubbard metal-insulator transitions, low dimensional electronic structures, and heavy fermion properties in various vanadium compounds using photoemission spectroscopy.

My focus in experimental condensed matter physics involves understanding the surface properties of correlated electron systems. With properties as superconductivity, colossalmagnetoresistance, ferroelectricity, and enhanced catalytic reactions, the immense potential from both academic and technological points of view are evident. The surfaces of such systems offer a unique opportunity to not only investigate the intricate coupling degrees of freedom responsible for such exotic phases but an opportunity to search for new phases. The strive for nanoscale applications, where surface properties dominate, emphasizes the importance of interfaces and reduced dimensionality.

I am a graduate student in Physics and I joined the Shen group in the summer of 2006. I am currently working on a project to research and develop Diamondoids, which are molecular crystals of diamond-like hydrocarbons. Little is known about the properties of the larger Diamondoids, so we are currently pursuing many different avenues of research on them. Possible applications include superconductivity, nano-scale devices, and field emission electronics. I find this project interesting because it enables me to do work in a broad range of disciplines including chemistry, material science, and electronics, while still being able to do pure physics research.

I graduated from Fudan University in Shanghai, China and am now in my third year of Ph.D. candidacy. My research interest currently focuses on charge (spin) density wave (CDW/SDW) ordering in complex materials, which include (Nd-doped) La_2-xSr_xCuO₄ high-temperature superconductor and R₂Te₅ rare earth telluride. Besides the major technique, ARPES, I am using (at SSRL/ALS/McCullough HeLM), I am developing an in-situ technique for the characterization of superconducting transition temperature of sample surfaces, which will serve my long-term interest in stepping into a largely unexplored area, the surface superconductivity.

I am a graduate student in the Applied Physics Department. I join the Shen group in summer 2007. I received a BS from Brown University. I am working on developing a Near Field Microwave Microscope. This technique probes the electrical properties of a material, i.e. the dielectric constant and conductivity.  Our primary goals are improving the sensitivity of the technique and looking for possible applications such as studying ferro electric material, nano particles in biological system, and system with a first order phase transition near room temperature.

I am currently a graduate student in physics department and I received my BS degree in Tsinghua University, China. Now I'm working on developing the new time- and spin- resolved photoemission spectrometer. With the capability of detecting electron spins, I'm looking forward to study novel systems such as magnetic material and spin-orbit coupling system. And also, with the time resolution, we will be able to study system's dynamical behavior, which would lead us to some really interesting physics problems.

My interest is to use angle-resolved photoemission spectroscopy, or ARPES, to study the mechanism of high-Tc superconductivity. Recent years, the resolution is improved enough to see the signature of bosonic mode coupling in the form of “kink” in ARPES spectra of cuprates. My current study of the one-layer bismuth cuprate, Bi2201, is to see the doping dependent effect in the electron dispersion which may shed some light on the mechanism of high-Tc superconductivity. Early studies with my mentors were on Sr₂RuO₄ and Ca_2-xNaxCuO₂Cl₂.

I received a Diplom from the Julius-Maximilians-Universitt Wrzburg in Germany in 2006. I was doing PES on the Kondo system CeSi2 then. I have always been fascinated with solid state physics and how systems with a vast amount of particles and countless interactions and correlations sometimes organize themselves to such a high degree that description and understanding is actually possible, and so I continue by pursuing a PhD degree in Stanford in a very similar area: Complementary to the p-doped cuprate high transition temperature superconductors --- as studied by my fellow team mates ---, the e-doped ones have a very similar doping-temperature phase diagram. I am fascinated by the question of how much of the underlying physics of those two is the same. ARPES for me is the most direct and elegant probe to learn more about these e-doped cuprates, like NCCO, PCCO, etc.

I am a graduate student in the department of physics, and I began work in the Shen lab in 2008. I am interested in photoexcitation with an eye towards energy applications. The Shen group is intimately familiar with the processes of photoexcitation and photoemission. My hope is to apply this enormous expertise to gain unique insight into novel solar energy designs.

I graduated from Cornell University in 2007 with a BS in Engineering Physics. I'm now a graduate student in the Department of Physics. I'm fascinated by the way in which the countless constituents of matter, and the interactions between them, conspire to give a material its macroscopic properties-- not only properties that we're familiar with, but also exotic and counterintuitive properties. My goals for future work include:
1) to use photoemission to study magnetic materials and the high-temperature superconductors; and
2) to help advance the technology used to probe these materials. Currently, I'm contributing to the development of our time- and spin- resolved spectrometer

I am a graduate student in the Applied Physics department, and I joined the Shen lab in 2007. My interests lie in strongly-correlated transition metal oxides, and in particular, the cuprate high-temperature superconductors. Whereas BCS superconductivity emerges from a well understood Fermi-liquid normal state, the "normal" state of high temperature superconductors--the pseudogap --is still unexplained. To that end, I am using Angle Resolved Photoemission Spectroscopy to study the pseudogap of Bi-2212. As the resolution of ARPES has improved in recent years, we are able to get a detailed picture of the phase diagram above T_c as a function of doping. From this, progress can be made towards understanding the origin of the pseudogap and its relation to superconductivity.

I am a graduate student in the physics department. I joined the Shen group in the spring of 2008. When I was an undergraduate at MIT, I studied the high Tc cuprate BSCO using STM, and have since been very fascinated by the high level of ordering in strongly correlated systems and the wide range of unusual and exotic properties that arise. I look forward to using ARPES to probe and study electron dynamics and ordering phenomena in rich systems such as strontium ruthenate and cuprates, and to contribute to piecing together the larger picture that is fundamental to all these correlated systems.

As an undergrad in Engineering Physics, my interest lies in learning how to effectively merge principles of Physics with Engineering. Working with Professor Shen's team allows me to develop an appreciation for applied Physics and simultaneously provide a hands-on, practical approach to developing Engineering applications.

Former Members of Shen Group