Talk 1:
Fermi-Liquid T2 Resistivity: Dynamical Mean-Field Theory Meets Experiment
Cyrus Dreyer, Stony Brook and Flatiron Institute
In metals, Fermi-liquid (FL) theory serves as the basis for understanding transport. A T2 behavior of the DC resistivity is often taken as a signature of FL electron-electron scattering, however such a scaling is sometimes observed in unexpected regimes. For example, SrVO3 and SrMoO3, both moderately-correlated high-conductivity perovskites, exhibit T2 up to hundreds of Kelvins where electron-phonon scattering is expected to dominate over electron-electron. In this talk I will describe how density-functional theory combined with dynamical mean-field theory (DMFT) can be used to elucidate this behavior, uncovering a “hidden” low-temperature regime dominated by FL electron-electron scattering, and identifying the higher-temperature T2 scaling as being caused by scattering with phonons. I will show how these insights are enabled by recent computational advances, and the use of known FL scaling properties to overcome the challenges of obtaining computationally precise scattering rates in high-conductivity materials. Finally, I will discuss the implications for interpreting temperature scaling of DC resistivity and discovering/designing high conductivity oxides.
Talk 2:
Intrinsic Strange Metal due to Heavy-Fermion Quantum Criticality
Andreas Gleis, Rutgers University
I present a cellular dynamical mean-field theory (CDMFT) plus Numerical Renormalization Group (NRG) approach to study quantum criticality in the periodic Anderson model (PAM). The CDMFT phase diagram of the PAM contains a Kondo breakdown (KB) quantum critical point (QCP). At zero temperature, this KB-QCP marks a continuous transition between two Fermi liquid phases, which differ in their Fermi surface volumes. I discuss the differences between these Fermi liquid phases in terms of their single-particle properties. NRG further enables us to study the quantum critical region governed by the QCP, where we find non-Fermi liquid behavior with strange-metal-like features such as a linear-in-T resistivity, dynamical scaling, and a logarithmic temperature dependence of the Sommerfeld coefficient. I discuss the optical properties of this strange metal regime, emphasize the role of vertex contributions, and contrast our results with marginal-Fermi-liquid behavior.