Site web ESPCI
Jeudi 11 Mai 2017 à 14h00
Amphi Holweck, Esc C
1ème etage
TRANSPORT IN STRONGLY CORRELATED BAD METALS
Abstract :
The standard paradigm for transport in metals relies on the existence of quasiparticles. Transport coefficients such as electrical and thermal conductivities can then be calculated using e.g. Boltzmann equations. However, such an approach fails in the so-called `bad metal’ regime, when the quasiparticle mean free paths become comparable to the wavelengths of the electron and/or highest frequency phonon. Transport in non-quasiparticle regimes requires a new framework and has become a subject of intense theoretical and experimental efforts in recent years. In particular, the diffusivity was singled out as a key observable for incoherent non-quasiparticle transport, possibly subject to fundamental quantum mechanical bounds. Following a review of previous experimental results on bad metallic behavior, we will introduce new results on transport in strongly correlated electron systems with strong electron-phonon interaction. These results suggest that when neither well-defined electron nor phonon quasiparticles are present, thermal transport exhibits a collective behavior of a `soup’ of strongly coupled electrons and phonons characterized by a diffusion constant $D\sim v_B^2\tau$, where $v_B$ is the `soup’ velocity and scattering of both electrons and phonons saturate a quantum thermal relaxation time $\tau \sim \hbar/k_BT$