Disorder versus two transport lifetimes in a strongly correlated electron liquid

Abstract

We report on angle-dependent measurements of the sheet resistances and Hall coefficients of electron liquids in SmTiO3/SrTiO3/SmTiO3 quantum well structures, which were grown by molecular beam epitaxy on (001) DyScO3. We compare their transport properties with those of similar structures grown on LSAT [(La0.3Sr0.7)(Al0.65Ta0.35)O3]. On DyScO3, planar defects normal to the quantum wells lead to a strong in-plane anisotropy in the transport properties. This allows for quantifying the role of defects in transport. In particular, we investigate differences in the longitudinal and Hall scattering rates, which is a non-Fermi liquid phenomenon known as lifetime separation. The residuals in both the longitudinal resistance and Hall angle were found to depend on the relative orientations of the transport direction to the planar defects. The Hall angle exhibited a robust T 2 temperature dependence along all directions, whereas no simple power law could describe the temperature dependence of the longitudinal resistances. Remarkably, the degree of the carrier lifetime separation, as manifested in the distinctly different temperature dependences and diverging residuals near a critical quantum well thickness, was completely insensitive to disorder. The results allow for a clear distinction between disorder-induced contributions to the transport and intrinsic, non-Fermi liquid phenomena, which includes the lifetime separation.

Non-Fermi liquids in oxide heterostructures

“…In the cuprates, the 0-K divergence in scattering rates has been explained with anisotropies in the elastic scattering rates [71]. In a recent study of SmTiO 3 / SrTiO 3 /SmTiO 3 quantum wells, we showed that disorder affected the residuals in both the Hall angle and longitudinal resistances, but it did not affect their 0-K divergence [70].…”

“…The resistance is ~ T 5/3 above ~100 K, while the Hall angle is always ~ T 2 [69]. Lifetime separation was also investigated in quantum wells of SrTiO 3 [57,70], such as formed in SmTiO 3 /SrTiO 3 / SmTiO 3 heterostructures, which contain mobile charge densities on order of 7 × 10 14 cm −2 and which exhibit numerous correlated phenomena, such as itinerant magnetism and pseudo gaps, when their thicknesses are reduced to a few atomic planes. These studies showed that the lifetime separation can have two components, namely the different temperature dependencies of Hall angle and longitudinal resistances, as seen in figure 4, but also a divergence in their 0-K residuals [57].…”

Highly Sensitive and Precise Analysis of SF6 Decomposition Component CO by Multi-comb Optical-feedback Cavity Enhanced Absorption Spectroscopy with a 2.3 μm Diode Laser

“…Recently, trace gas sensors based on tunable diode laser absorption spectroscopy (TDLAS) are widely used due to their high detection sensitivity and selectivity as well as fast response time, which permits online monitoring of target gas concentrations 7–10 . The basic principle of tunable diode laser absorption spectroscopy can be described briefly as: (a) The emission wavelength of diode laser, is tuned over the characteristic absorption lines of a target gas; (b) Then, the gas concentration can be determined through the reduction of the measured signal intensity caused by gas absorption 11 .…”