Disorder versus two transport lifetimes in a strongly correlated electron liquid

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 T2 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.Comment: In press, Sci. Re

Growth of strontium ruthenate films by hybrid molecular beam epitaxy

We report on the growth of epitaxial Sr2RuO4 films using a hybrid molecular beam epitaxy approach in which a volatile precursor containing RuO4 is used to supply ruthenium and oxygen. The use of the precursor overcomes a number of issues encountered in traditional MBE that uses elemental metal sources. Phase-pure, epitaxial thin films of Sr2RuO4 are obtained. At high substrate temperatures, growth proceeds in a layer-by-layer mode with intensity oscillations observed in reflection high-energy electron diffraction. Films are of high structural quality, as documented by x-ray diffraction, atomic force microscopy, and transmission electron microscopy. The method should be suitable for the growth of other complex oxides containing ruthenium, opening up opportunities to investigate thin films that host rich exotic ground states.Comment: In press, APL Mate

What can we Learn about Research Narratives from Professional Storytellers?

This short note on practice reflects on how “research narrative” is a much-used, but misunderstood term. Compelling stories about our research are important: for public-facing communications and for academic tenure confirmation and promotion. They are also important for researchers to gain a clearer sense of their own vision and values in the research process: they are not just a communication skill, they’re a career skill. But often researchers in STEM disciplines do not have the practical skills to write stories. We draw on our own practice as creative writers to share some simple and effective methods to bring arts expertise into STEM research narratives

Response of the lattice across the filling-controlled Mott metal-insulator transition of a rare earth titanate

The lattice response of a prototype Mott insulator, SmTiO3, to hole doping is investigated with atomic-scale spatial resolution. SmTiO3 films are doped with Sr on the Sm site with concentrations that span the insulating and metallic sides of the filling-controlled Mott metal-insulator transition (MIT). The GdFeO3-type distortions are investigated using an atomic resolution scanning transmission electron microscopy technique that can resolve small lattice distortions with picometer precision. We show that these distortions are gradually and uniformly reduced as the Sr concentration is increased without any phase separation. Significant distortions persist into the metallic state. The results present a new picture of the physics of this prototype filling-controlled MIT, which is discussed.Comment: Accepted, Phys. Rev. Let

Making intellectual room for persona studies: a new consciousness and a shifted perspective

It is an enormously difficult—and perhaps impossible, but ultimately important—task to comprehensively define the contemporary moment through a particular concept. This introduction and this journal make the claim that both in a pervasive way and to a pandemic extent, there is enormous activity and energy in the production, construction, and exhibition of personas. Something quite extraordinary has shifted over the last twenty years that has led to this intensive focus on constructing strategic masks of identity. The catalyst is the development of online culture and its invocation to personalize the expression of a public self—essentially a persona—regularly and incessantly. This culture of producing and monitoring our public selves is the focus of this journal as online culture blends with everyday culture and leads to an insistent proliferation of personas for both presentation and for strategic purposes in order to manage very new notions of value and reputation. The task of investigating persona is complex, and is dependent on connections and intersections across an array of disciplines. This journal and the field of Persona Studies is designed to serve as a site for this essential work of comprehending, analysing, and critiquing persona, and to allow disciplines to intersect, exchange ideas, and debate the play of persona historically and in contemporary culture