NEWS: The CQM Distinguished Lecture series has been established in the Fall of 2015 to bring to Stony Brook University the renown experts in the physics of quantum matter.
April – May 2017
Dr. Kin Chung Fong, Raytheon BBN Technologies
Putting hydrodynamic into solid state
Despite of the strong Coulomb interaction, electrons in simple metal behave as a non-interacting Fermi gas with long-lived quasi-particle excitation. However, weak screening near the charge neutrality point of the massless Dirac fermions in graphene can lead to a new collective behavior described by hydrodynamics. By listening to the Johnson noise of the electrons, we are able to probe simultaneously the thermal and electrical transport of the Dirac fluid and observe how it departs from Fermi liquid physics. At high temperature near the neutrality point, we find a strong enhancement of the thermal conductivity and breakdown of Wiedemann-Franz law in graphene. This is attributed to the non-degenerate electrons and holes forming a strongly coupled Dirac fluid.
Ref: Science 351, 1058 (2016)
Iron based superconductors have been attracting considerable attention since their discovery in 2008 . In particular, simple binary iron chalcogenides have recently emerged to the frontier of research due to traces of superconducting critical temperatures (Tc’s) similar to copper oxide high-Tc superconductors . In this talk I will discuss characteristics of FeX and KxFe2-yX2 (X=Se,S). I will mention in a nutshell pair breaking mechanism [4,5,6,7,8], magnetic states [9,10] and critical currents whereas I with focus on the normal states in high magnetic fields as T → 0 connected with crystal structure characteristics [18,19]. The presentation will also include brief discussion on magnetic states in semiconducting crystal structures with FeX building blocks.