The Lorenz ratio as a guide to scattering contributions to transport in strongly correlated metals.

In many physical situations in which many-body assemblies exist at temperature , a characteristic quantum-mechanical time scale of approximately [Formula: see text] can be identified in both theory and experiment, leading to speculation that it may be the shortest meaningful time in such circumstances. This behavior can be investigated by probing the scattering rate of electrons in a broad class of materials often referred to as "strongly correlated metals". It is clear that in some cases only electron-electron scattering can be its cause, while in others it arises from high-temperature scattering of electrons from quantized lattice vibrations, i.

Determination of the dynamic Young's modulus of quantum materials in piezoactuator-driven uniaxial pressure cells using a low-frequency AC method.

We report on a new technique for measuring the dynamic Young's modulus, E, of quantum materials at low temperatures as a function of static tuning strain, ϵ, in piezoactuator-driven pressure cells. In addition to a static tuning of stress and strain, we apply a small-amplitude, finite-frequency AC (1 Hz ≲ ω ≲ 1000 Hz) uniaxial stress, σac, to the sample and measure the resulting AC strain, ϵac, using a capacitive sensor to obtain the associated modulus E. We demonstrate the performance of the new technique through proof-of-principle experiments on the unconventional superconductor Sr2RuO4, which is known for its rich temperature-strain phase diagram.

In-Plane Magnetic Penetration Depth in Sr_{2}RuO_{4}: Muon-Spin Rotation and Relaxation Study.

We report on measurements of the in-plane magnetic penetration depth (λ_{ab}) in single crystals of Sr_{2}RuO_{4} down to ≃0.015  K by means of muon-spin rotation-relaxation. The linear temperature dependence of λ_{ab}^{-2} for T≲0.

A spatially resolved optical method to measure thermal diffusivity.

We describe an optical method to directly measure the position-dependent thermal diffusivity of reflective single crystal samples across a broad range of temperatures for condensed matter physics research. Two laser beams are used, one as a source to locally modulate the sample temperature, and the other as a probe of sample reflectivity, which is a function of the modulated temperature. Thermal diffusivity is obtained from the phase delay between source and probe signals.