In contrast to the Landau paradigm, a metal-insulator transition (MIT), driven purely by competition between itinerance and localization and unaccompanied by any conventional (e.g, magnetic) ...order-disorder instabilities, admits no obvious local order parameter. Here, we present a detailed analysis of the quantum criticality in magneto-transport data on the alloy Nb\(_{1-x}\)Ti\(_{x}\)N across a Ti-doping-driven a MIT. We demonstrate, for the first time, clear and novel quantum criticality reflected in the full conductivity tensor across the MIT. Wide ranging, comprehensive accord with recent theoretical predictions strongly suggests that these unanticipated findings are representative of a continuous MIT of the band-splitting type, rather than a conventional Anderson disorder or a "pure" correlation-driven first-order Mott type.
The study aims to understand the effect of UV exclusion and arbuscular mycorrhizal fungi (AMF) inoculation on the photosynthetic parameters of soybean. The study was conducted in nursery bags and ...plants were grown under iron mesh covered with UV cut-off filters. The plants grown under the exclusion of UV with AMF inoculation (I) showed higher photosynthetic pigments, carbonic anhydrase activity, reduced internal CO2 concentration, enhanced transpiration rate, and stomatal conductance as well as improved photosynthetic rate over uninoculated plants. Moreover, -UVB+I and -UVAB+I plants exhibited an increased performance index, the activity of the water-splitting complex on the donor side of PSII, and the concentration of active PSII reaction centers per excited cross-section. Overall, UV-excluded and AMF-inoculated plants showed the highest quantum yield of PSII and rate of photosynthesis. Our study will pave the way for future investigation to identify the possible role of UV exclusion and AMF in improving the photosynthetic performance for better yield of soybean.
A single transport relaxation rate governs the decay of both, longitudinal and Hall currents in Landau Fermi Liquids (LFL). Breakdown of this fundamental feature, first observed in cuprates and ...subsequently in other three-dimensional correlated systems close to (partial or complete) Mott metal-insulator transitions, played a pivotal role in emergence of a non-Landau Fermi liquid paradigm in higher dimensions \(D(>1)\). Motivated hereby, we explore the emergence of this "two relaxation rates" scenario in the Hubbard-Falicov-Kimball model (HFKM) using the dynamical mean-field theory (DMFT). Specializing to \(D=3\), we find, beyond a critical FK interaction, that two distinct relaxation rates governing distinct temperature (\(T\)) dependence of the longitudinal and Hall currents naturally emerges in the non-LFL metal. We rationalize this surprising finding by an analytical analysis of the structure of charge and spin correlations in the underlying impurity problem, and point out good accord with observations in the famed case of V\(_{2-y}\)O\(_3\) near the MIT.
Strain tuning is increasingly being recognized as a clean tuning parameter to induce novel behavior in quantum matter. Motivated by the possibility of straining graphene up to \(20\) percent, we ...investigate novel quantum criticality due to interplay between strain-induced anisotropic band structure and critical antiferromagnetic spin fluctuations (AFSF) in this setting. We detail how this interplay drives \((i)\) a quantum phase transition (QPT) between the Dirac-semimetal-incoherent pseudogapped metal-correlated insulator as a function of strain (\(\epsilon\)), and \((ii)\) critical AFSF-driven divergent nematic susceptibility near critical strain (\(\epsilon_{c}\)) manifesting as critical singularities in magneto-thermal expansion and Gr\"uneisen co-efficients. The correlated band insulator at large strain affords realization of a two-dimensional dimerized spin-singlet state due to this interplay, and we argue how doping such an insulator can lead to a spin-charge separated metal, leading to anomalous metallicity and possible unconventional superconductivity. On a wider front, our work serves to illustrate the range of novel states realizable by strain-tuning quantum materials.
In contrast to the seminal weak localization prediction of a non-critical Hall constant (\(R_{H}\)) at the Anderson metal-insulator transition (MIT), \(R_{H}\) in quite a few real disordered systems ...exhibits both, a strong \(T\)-dependence and critical scaling near their MIT. Here, we investigate these issues in detail within a non-perturbative "strong localization" regime using cluster-dynamical mean field theory (CDMFT). We uncover \((i)\) clear and unconventional quantum-critical scaling of the \(\gamma\)-function, finding that \(\gamma(g_{xy})\simeq\) log\((g_{xy})\) over a wide range spanning the continuous MIT, very similar to that seen for the longitudinal conductivity, \((ii)\) strongly \(T\)-dependent and clear quantum critical scaling in both transverse conductivity and \(R_{H}\) at the MIT. We find that these surprising results are in comprehensive and very good accord with signatures of a novel kind of localization in disordered NbN near the MIT, providing substantial support for our "strong" localization view.
The interplay between multiple bands, sizable multi-band electronic correlations and strong spin-orbit coupling may conspire in selecting a rather unusual unconventional pairing symmetry in layered ...Sr\(_{2}\)RuO\(_{4}\). This mandates a detailed revisit of the normal state and, in particular, the \(T\)-dependent incoherence-coherence crossover. Using a modern first-principles correlated view, we study this issue in the actual structure of Sr\(_{2}\)RuO\(_{4}\) and present a unified and quantitative description of a range of unusual physical responses in the normal state. Armed with these, we propose that a new and important element, that of dominant multi-orbital charge fluctuations in a Hund's metal, may be a primary pair glue for unconventional superconductivity. Thereby we establish a connection between the normal state responses and superconductivity in this system.
PDF
