Neutron Scattering Study of Low Energy Spin Excitations in the FeTe/Se Superconductors
| Date/Time: | Wednesday, 01 Apr 2015 from 4:10 pm to 5:00 pm |
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| Location: | Physics 0003 |
| Phone: | 515-294-5441 |
| Channel: | College of Liberal Arts and Sciences |
| Actions: | Download iCal/vCal | Email Reminder |
ABSTRACT: Research on high temperature superconductivity has been one of the most active fields in condensed matter physics during the last three decades. There has been extensive interest in both finding new superconductors with higher transition temperatures, and in understanding the fundamental mechanisms. The recently discovered Fe-based superconductors have attracted much attention from both the theoretical and experimental aspects. Spin fluctuations are believed to play important roles in mediating electron pairing in the both Fe-based superconductors and the high-Tc cuprates. The neutron scattering technique is a powerful tool for studying magnetism in superconductors, which can provide important information about the momentum and energy dependence of magnetic correlations. Similar to the case in other high-Tc families including the high-Tc cuprates, a spin-resonance and spin-gap are commonly observed in Fe-based superconductors when the system enters the superconducting phase. Here I will present results suggesting that in addition to these common signatures, a dramatic change in the spin-dispersion is observed in the Fe(Te/Se) superconductor ("11" compound). The low energy spin excitations from the superconducting and non-superconducting phases in this system are distinctively different. Implications of these results and possible future work will also be discussed.
BIO: Zhijun Xu was born in Shanghai, China in 1981. He obtained his B. Sc. (2004) from Fudan University in China, and Ph. D. (2011) from the graduate school and university center of CUNY (City University of New York) in the U.S. He was a research associate (2011- 2013) at Brookhaven national laboratory and a postdoctoral scholar at UC Berkeley since 2013. He has worked on growth of large high-quality single crystal and studying materials properties using neutron scattering. Understanding the magnetic and lattice structures and dynamics in complex materials systems such as high-Tc superconductors, multiferroics, and ferroelectrics are current main areas of his research.