Pantheon SEMPARIS Le serveur des séminaires parisiens Paris

Status Confirmed
Seminar Series LPA
Subjects cond-mat
Date Thursday 18 January 2018
Time 13:30
Institute LPA
Seminar Room L 378-380
Speaker's Last Name Grushin
Speaker's First Name Adolfo
Speaker's Email Address
Speaker's Institution Institut Neel, Grenoble
Title Large and quantized non-linear responses in topological metals
Abstract In this talk I will discuss two of our recent results concerning nonlinear responses of topological metals. The first is the prediction of a quantized circular photogalvanic effect, the part of the photocurrent which changes sign when the light’s polarization flips. We find it is quantized in units of a large universal constant e^3/h^2 times the Weyl monopole charge in mirror free Weyl semimetals (e.g. SrSi2) and three-dimensional Rashba materials (e.g. doped Te). The second is the measurement and modeling of the second harmonic generation in TaAs, the frequency doubling of an incident pulse upon reflection or transmission. We find it experimentally to be extremely large and anisotropic compared to materials in the same symmetry class such as GaAs. We show that these features are well captured phenomenologically in terms of a model of coupled ferroelectric chains, which suggests that TaAs is close to saturating a photocurrent bound that we derive. Quantized circular photogalvanic effect in Weyl semimetals, Fernando de Juan, Adolfo G. Grushin, Takahiro Morimoto, Joel E. Moore Nature Communications 8, 15995 (2017)
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