Tuesday, 17 November 2015, 4:00-5:00 PM, Physics 147
Interplay of Superconductivity an Structural Transition/CDW State
Dr. Huiqui Yuan, Professor, Center for Correlated Matter & the Dept. of Physics, Zhejiang University
The interplay of superconductivity and charge-density-wave (CDW) state remains a frontier topic in condensed matter physics. The newly discovered superconductors BaPt2As2 and EuFBiS2 showed evidence for the coexistence of superconductivity (SC) and a possible CDW state.
To study the possible interplays of SC and CDW in these compounds, in this talk I will present our recent measurements of the electrical resistivity, magnetic susceptibility and XRD diffraction under pressure, which leads to rich temperature-pressure phase diagrams.
Friday, 10 April 2015, 12:00-1:00 PM, Physics 152
Discovery of an Unconventional Superconducting Phase on the 3-D Dirac Semi-metal Cd3As2
Dr. Goutam Sheet, Assistant Professor of Physics & DST Ramanujan Fellow, Indian Institute of Science Education and Research (ISER), Mohali, India
In this talk I will present our recent work on the discovery of a novel superconducting phase at mesoscopic point-contacts between a metal and the 3-D semi-metal Cd3As2. Bulk Cd3As2 is not known to be a superconductor but when mesoscopic point-contacts are formed on Cd3As2 the point-contacts show superconductivity up to a critical temperature of 8 K. By performing Andreev reflection spectroscopy on such point-contacts we have measured an energy gap which is high (6 meV) and does not change much with temperature up to 13 K. This indicates an unconventional nature of the superconducting phase. We also see a pronounced zero-bias conductance peak which might be attributed to topological superconductivity. Furthermore, from our experiments with ferromagnetic point-contacts on Cd3As2 we show the signature of a p-wave component in the order parameter of the new superconducting phase.
Thursday, 2 April 2015, 3:30-4:30 PM, Physics 137
Acoustic Studies of Two-Dimensional Structures with High Conductivity
Dr. Alexey V. Suslov, National High Magnetic Field Lab, Florida State University
I will give a review of DC field facility at the National High Magnetic Field Laboratory and present a novel detector, which I recently designed and built for ultrasonic experiments in High magnetic fields. I will describe our results obtained by the surface acoustic wave technique on two–‐dimensional (2D) structures with quantum Hall effect. We use this technique for studies of complex ac conductivity of 2D carriers.
Measurements on a p–‐GeSi/Ge/GeSi (p=6×10**11 cm–‐2) single quantum well were performed in tilted magnetic fields and revealed that the in-plane component of the magnetic field affects the g-factor and the cyclotron effective mass of the holes.
Our studies of single 65nm quantum well AlGaAs/GaAs/AlGaAs structure (n=5×10**10 cm–‐2 and μ=8.5×10**6 cm2/Vs) were focused in the vicinity of the filling factor 1/5. In this region, observed frequency dependence of the ac conductivity is of a resonance nature. Such a behavior of ac conductivity could be interpreted as manifestation of a pinning mode of a Wigner crystal.