Statut  Confirmé 
Série  LPA 
Domaines  condmat 
Date  Jeudi 18 Janvier 2018 
Heure  13:30 
Institut  LPA 
Salle  L 378380 
Nom de l'orateur  Grushin 
Prenom de l'orateur  Adolfo 
Addresse email de l'orateur  
Institution de l'orateur  Institut Neel, Grenoble 
Titre  Large and quantized nonlinear responses in topological metals 
Résumé  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 threedimensional 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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