JHU Salon this Friday (Dec. 19): "History of superconductor and a family of new Fe superconductors of SmFeAsO1-xFx"

[zhangjun506]

Welcome to JHU Salon of this week; drinks and snacks will be served.

 

Time: December 19 (Friday), 5:00-6:30 PM

Place: Mergenthaler 526 (Homewood campus) 

 

Title: History of superconductor and a family of new Fe superconductors of SmFeAsO1-xFx

Presenter: TingYong Chen (Postdoc, Department of physics and astronomy)

Introduction:

 

Superconductivity is important in science as well as in application. A family of new Fe superconductors of SmFeAsO_1-xF_x and others have been discovered in 2008 that contain the puckered FeAs planes instead of the hallmark CuO₂ planes in the cuprate superconductors. Central to any superconductor is the nature of its superconducting gap, its value, its structure if any, its temperature dependence.  We used Andreev reflection spectroscopy to investigate the gap of these new (1111) Fe superconductors and its temperature dependence. Although the gap values and transition temperatures are different for the Fe superconductors with different F doping, the values of 2D/k_BT_C are all close to 3.53 that of a BCS s-wave superconductor. The gap is nearly isotropic with temperature dependence close to that of an s-wave superconductor. We did not find evidences of pseudogaps, but the spin density wave transition can induce spurious “pseudogaps” in the system. These characteristics of the Fe superconductors are dramatically different from those of the cuprate superconductors.

Dr. Tingyong Chen obtained his B.S. and M.S. from PKU in China, and received his Ph.D. from Johns Hopkins University (Physics). He is going to talk about his recent work of “Superconducting gap of Fe Superconductors” (Nature) with a brief history of superconductivity. He might remind many of you how boring Physics is but would like to discuss things that you’re interested in afterwards

 
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