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Materials with strongly correlated electrons often exhibit interesting physical properties. An example of these materials is the layered oxide perovskite Sr 2 RuO 4 , which has been intensively investigated due to its unusual properties. Whilst the debate on the symmetry of the superconducting state in Sr 2 RuO 4 is still ongoing, a deeper understanding of the Sr 2 RuO 4 normal state appears crucial as this is the background in which electron pairing occurs. Here, by using low-energy muon spin spectroscopy we discover the existence of surface magnetism in Sr 2 RuO 4 in its normal state. We detect static weak dipolar fields yet manifesting at an onset temperature higher than 50 K. We ascribe this unconventional magnetism to orbital loop currents forming at the reconstructed Sr 2 RuO 4 surface. Our observations set a reference for the discovery of the same magnetic phase in other materials and unveil an electronic ordering mechanism that can influence electron pairing with broken time reversal symmetry. Strontium Ruthenate, Sr 2 RuO 4 , displays a remarkable number of intriguing physical phenomena, from superconductivity, to strain-induced ferromagnetism. Here, using low-energy muon spectroscopy, Fittipaldi et al. demonstrate the existence of unconventional magnetism at the surface of Sr 2 RuO 4 in its normal state and without any applied strain.

A paradigmatic case of multi-band Mott physics including spin-orbit and Hund’s coupling is realized in Ca 2 RuO 4 . Progress in understanding the nature of this Mott insulating phase has been impeded by the lack of knowledge about the low-energy electronic structure. Here we provide—using angle-resolved photoemission electron spectroscopy—the band structure of the paramagnetic insulating phase of Ca 2 RuO 4 and show how it features several distinct energy scales. Comparison to a simple analysis of atomic multiplets provides a quantitative estimate of the Hund’s coupling J =0.4 eV. Furthermore, the experimental spectra are in good agreement with electronic structure calculations performed with Dynamical Mean-Field Theory. The crystal field stabilization of the d xy orbital due to c -axis contraction is shown to be essential to explain the insulating phase. These results underscore the importance of multi-band physics, Coulomb interaction and Hund’s coupling that together generate the Mott insulating state of Ca 2 RuO 4 . Detailed knowledge of the low-energy electronic structure is required to understand the Mott insulating phase of Ca 2 RuO 4 . Here, Sutter et al . provide directly the experimental band structure of the paramagnetic insulating phase of Ca 2 RuO 4 and unveil the electronic origin of its Mott phase.

A paradigmatic case of multi-band Mott physics including spin-orbit and Hund's coupling is realized in Ca RuO . Progress in understanding the nature of this Mott insulating phase has been impeded by the lack of knowledge about the low-energy electronic structure. Here we provide-using angle-resolved photoemission electron spectroscopy-the band structure of the paramagnetic insulating phase of Ca RuO and show how it features several distinct energy scales. Comparison to a simple analysis of atomic multiplets provides a quantitative estimate of the Hund's coupling J=0.4 eV. Furthermore, the experimental spectra are in good agreement with electronic structure calculations performed with Dynamical Mean-Field Theory. The crystal field stabilization of the d orbital due to c-axis contraction is shown to be essential to explain the insulating phase. These results underscore the importance of multi-band physics, Coulomb interaction and Hund's coupling that together generate the Mott insulating state of Ca RuO .

The single-layered ruthenate Sr2RuO4 is one of the most enigmatic unconventional superconductors. While for many years it was thought to be the best candidate for a chiral p-wave superconducting ground state, desirable for topological quantum computations, recent experiments suggest a singlet state, ruling out the original p-wave scenario. The superconductivity as well as the properties of the multi-layered compounds of the ruthenate perovskites are strongly influenced by a van Hove singularity in proximity of the Fermi energy. Tiny structural distortions move the van Hove singularity across the Fermi energy with dramatic consequences for the physical properties. Here, we determine the electronic structure of the van Hove singularity in the surface layer of Sr2RuO4 by quasi-particle interference imaging. We trace its dispersion and demonstrate from a model calculation accounting for the full vacuum overlap of the wave functions that its detection is facilitated through the octahedral rotations in the surface layer.

The strongly correlated insulatorCa2RuO4is considered as a paradigmatic realization of both spin-orbital physics and a band-Mott insulating phase, characterized by orbitally selective coexistence of a band and a Mott gap. We present a high resolution oxygenK-edge resonant inelastic x-ray scattering study of the antiferromagnetic Mott insulating state ofCa2RuO4. A set of low-energy (about 80 and 400 meV) and high-energy (about 1.3 and 2.2 eV) excitations are reported, which show strong incident light polarization dependence. Our results strongly support a spin-orbit coupled band-Mott scenario and explore in detail the nature of its exotic excitations. Guided by theoretical modeling, we interpret the low-energy excitations as a result of composite spin-orbital excitations. Their nature unveils the intricate interplay of crystal-field splitting and spin-orbit coupling in the band-Mott scenario. The high-energy excitations correspond to intra-atomic singlet-triplet transitions at an energy scale set by Hund’s coupling. Our findings give a unifying picture of the spin and orbital excitations in the band-Mott insulatorCa2RuO4.

Thyroid carcinomas comprise a broad spectrum of tumors with different clinical behaviors. On the one side, there are occult papillary carcinomas (PTC), slow growing and clinically silent, and on the other side, rapidly growing anaplastic carcinomas (ATC), which are among the most lethal human neoplasms. We have analysed the microRNA (miR) profile of ATC in comparison to the normal thyroid using a microarray (miRNACHIP microarray). By this approach, we found an aberrant miR expression profile that clearly differentiates ATC from normal thyroid tissues and from PTC analysed in previous studies. In particular, a significant decrease in miR-30d, miR-125b, miR-26a and miR-30a-5p was detected in ATC in comparison to normal thyroid tissue. These results were further confirmed by northern blots, quantitative reverse transcription–PCR analyses and in situ hybridization. The overexpression of these four miRs in two human ATC-derived cell lines suggests a critical role of miR-125b and miR-26a downregulation in thyroid carcinogenesis, since a cell growth inhibition was achieved. Conversely, no effect on cell growth was observed after the overexpression of miR-30d and miR-30a-5p in the same cells. In conclusion, these data indicate a miR signature associated with ATC and suggest the miR deregulation as an important event in thyroid cell transformation.

Understanding and controlling the transition between antiferromagnetic states having different symmetry content with respect to time-inversion and space-group operations are fundamental challenges for the design of magnetic phases with topologically nontrivial character. Here, we consider a paradigmatic antiferromagnetic oxide insulator, Ca 2 RuO 4 , with symmetrically distinct magnetic ground states and unveil a novel path to guide the transition between them. The magnetic changeover results from structural and orbital reconstruction at the transition metal site that in turn arise as a consequence of substitutional doping. By means of resonant X-ray diffraction we track the evolution of the structural, magnetic, and orbital degrees of freedom for Mn doped Ca 2 RuO 4 to demonstrate the mechanisms which drive the antiferromagnetic transition. While our analysis focuses on a specific case of substitution, we show that any perturbation that can impact in a similar way on the crystal structure, by reconstructing the induced spin–orbital exchange, is able to drive the antiferromagnetic reorganization.

Background and Aims In recent years, increasing summer temperature, coupled with reduced and erratic rainfall during the growing season, has induced accelerated fruit ripening in several regions, resulting in an undesirable increase in wine alcohol concentration. This study was designed to evaluate the impact of canopy and water management on grape sugar and flavonoid accumulation, with the goal of reducing wine alcohol concentration while conserving or enhancing the concentration of phenolic substances. Methods and Results In 2011 and 2012, two irrigation treatments (I – irrigated and DI – deficit irrigated) and two canopy heights (HC – high canopy and SC – short canopy) were applied in a Merlot vineyard. No interactions between treatments were observed, and thus independent results were obtained; DI berries had significantly higher sugar concentration (+5%) than that of I in both years and higher wine alcohol concentration only in 2012. Short canopy berries had lower sugar concentration (−4%) and lower wine alcohol (−8%) (only in 2011) than that of HC. Anthocyanins and tannins in berry and wine were increased by water deficit and not affected by severe trimming. Conclusions Deficit irrigation did not reduce berry sugar concentration and wine alcohol concentration but did enhance desirable wine attributes. Berry sugar concentration and alcohol concentration in wine were reduced by SC in one of the two seasons. Water deficit and severe trimming showed independent effects on berry composition. Significance of the Study Severe canopy reduction at early stages of ripening can reduce sugars without affecting the accumulation of anthocyanins in Merlot. Conversely, DI applied before veraison, despite promoting anthocyanins accumulation, may also increase berry sugar concentration at harvest.

Background and Aims In recent years, increasing summer temperature, coupled with reduced and erratic rainfall during the growing season, has induced accelerated fruit ripening in several regions, resulting in an undesirable increase in wine alcohol concentration. This study was designed to evaluate the impact of canopy and water management on grape sugar and flavonoid accumulation, with the goal of reducing wine alcohol concentration while conserving or enhancing the concentration of phenolic substances. Methods and Results In 2011 and 2012, two irrigation treatments (I - irrigated and DI - deficit irrigated) and two canopy heights (HC - high canopy and SC - short canopy) were applied in a Merlot vineyard. No interactions between treatments were observed, and thus independent results were obtained; DI berries had significantly higher sugar concentration (+5%) than that of I in both years and higher wine alcohol concentration only in 2012. Short canopy berries had lower sugar concentration (-4%) and lower wine alcohol (-8%) (only in 2011) than that of HC. Anthocyanins and tannins in berry and wine were increased by water deficit and not affected by severe trimming. Conclusions Deficit irrigation did not reduce berry sugar concentration and wine alcohol concentration but did enhance desirable wine attributes. Berry sugar concentration and alcohol concentration in wine were reduced by SC in one of the two seasons. Water deficit and severe trimming showed independent effects on berry composition. Significance of the Study Severe canopy reduction at early stages of ripening can reduce sugars without affecting the accumulation of anthocyanins in Merlot. Conversely, DI applied before veraison, despite promoting anthocyanins accumulation, may also increase berry sugar concentration at harvest.

Understanding and controlling the transition between antiferromagnetic states having different symmetry content with respect to time-inversion and space-group operations are fundamental challenges for the design of magnetic phases with topologically nontrivial character. Here, we consider a paradigmatic antiferromagnetic oxide insulator, Ca$$_{2}$$2 RuO$$_{4}$$4 , with symmetrically distinct magnetic ground states and unveil a novel path to guide the transition between them. The magnetic changeover results from structural and orbital reconstruction at the transition metal site that in turn arise as a consequence of substitutional doping. By means of resonant X-ray diffraction we track the evolution of the structural, magnetic, and orbital degrees of freedom for Mn doped Ca$$_{2}$$2 RuO$$_{4}$$4 to demonstrate the mechanisms which drive the antiferromagnetic transition. While our analysis focuses on a specific case of substitution, we show that any perturbation that can impact in a similar way on the crystal structure, by reconstructing the induced spin–orbital exchange, is able to drive the antiferromagnetic reorganization.