Résultats de recherche pour « Universal incoherent metallic transport »

This paper presents an experimental benchmarking framework for evaluating phase retrieval consistency between the transport of intensity equation (TIE) and spatial axial shearing–based Incoherent Digital Holography (IDH) in fluorescence imaging. While TIE provides a non-interferometric, intensity-based approach for phase retrieval, its quantitative reliability under incoherent imaging conditions remains insufficiently validated against coherence-based techniques. Using a unified switchable experimental platform that ensures identical imaging conditions, we directly compare phase distributions retrieved by TIE and IDH from the same fluorescent objects. The IDH system employs spatial axial shearing and four-step phase shifting to reconstruct the complex spatial coherence function, providing a coherence-guided benchmark for comparison. Experimental results demonstrate strong agreement in the spatial extent and curvature of the retrieved phase profiles, while statistical analysis further confirms good consistency between the two methods across multiple fluorescent bead measurements. Under paraxial propagation conditions (Fresnel number ( N F > 1), TIE reconstructions show close agreement with both IDH and the conventional fluorescence reference image, whereas coherence-guided IDH remains more robust at larger defocus distances. The proposed benchmarking framework provides an experimental basis for assessing the reliability and limitations of TIE-based phase retrieval in incoherent fluorescence imaging.

Incoherent twin boundaries (ITBs) can significantly affect the mechanical properties of twin-structured metals. However, most previous studies have focused on the deformation mechanism of the coherent twin boundary (CTB), and metals with ITB-accommodated plasticity still require further investigation. In this study, deformation mechanisms of FCC-structured nanocrystal metals with ITBs were investigated using molecular dynamic (MD) simulations. We revealed that three deformation mechanisms occur in metals with ITBs. The first type of deformation was observed in Au, where the plasticity is governed by partial dislocation intersections with CTBs or reactions with each other to form Lomer–Cottrell (L–C) locks. In the second type, found in Al, the deformation is governed by reversible ITB migration. The third type of deformation, in Ni and Cu, is governed by partial dislocations emitted from the ITB or the tips of the stacking faults (SFs). The observed L–C lock formation, as well as the reversible ITB migration and partial dislocation emission from the tips of SFs, have rarely been reported before.

There is growing interest in a possible connection between incoherent metallic conduction and high temperature superconductivity, that is exemplified by the behaviour of the parent compounds of the new iron-pnictide high-temperature superconductors. We have recently discovered very incoherent behaviour in the non-superconducting arsenide, FeCrAs. This material shows a non-metallic resistivity that rises with decreasing temperature without saturation or a gap, over three decades of temperature, from 80 mK to 800 K. We briefly review this behaviour, and address the question of disorder: how to test for the presence of disorder in a system where the scattering rate inferred from the resistivity is highly abnormal, and how to produce single crystals with low levels of disorder. Our discussion will focus on magnetic properties. FeCrAs is a partly frustrated magnetic system with a Nèel temperature TN that depends on sample quality, a sample-dependent spin freezing temperature TF < TN, and magnetic hysteresis that depends strongly on preparation conditions due to ferromagnetic minority phases in disordered samples.