Arnold Sommerfeld Center

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Mixed-valence insulators with neutral Fermi-surfaces

Debanjan Chowdhury, MIT Cambridge USA

07.09.2017 at 10:00 

Samarium hexaboride is a classic three-dimensional mixed valence system with a high-temperature metallic phase that evolves into a paramagnetic charge insulator below 40 kelvin. A number of recent experiments have suggested the possibility that the low-temperature insulating bulk hosts electrically neutral gapless fermionic excitations. In this talk, I will describe a new phase of matter—composite exciton Fermi liquid— a mixed valence insulator with a three dimensional fermi-surface of a neutral fermion, the “composite exciton”. I will describe the mechanism responsible for the formation of such excitons, discuss the phenomenology of the composite exciton Fermi-liquids and make comparison to experiments in Samarium hexaboride.

A 450, Theresienstr. 37