Hypothesis: Interactions across incredibly thin layers of fluids, known as thin films, underpin many important processes involving colloids, such as wetting-dewetting phenomena. Often in these systems, thin films are composed of complex fluids that contain dispersed components, such as spherical micelles, giving rise to oscillatory structural forces due to preferential layering under confinement. Modelling of thin film dynamics involving Derjaguin-Landau-Verwey-Overbeek (DLVO) type forces has been widely reported using the Stokes-Reynolds-Young-Laplace (SRYL) model, and we hypothesize that this theory can be extended to a concentrated micellar system by including an oscillatory structural force term in the disjoining pressure.
Experiments: We study the drainage behaviour of thin films comprising sodium dodecyl sulfate (SDS) micelles across a range of concentrations and interaction conditions between an air bubble and a mica disk using a custom-built dual-wave interferometry apparatus.
Findings: Early-stage film behaviour is dominated by hydrodynamics, which can be well reproduced by the SRYL model. However, experimental profiles drain significantly faster than predicted, transitioning into a structural force dominated phase characterised by four types of film ripping instabilities that we term 'waving', 'ridging', 'webbing', and 'hole-sheeting'. These instabilities were mapped according to SDS concentration and approach velocity, providing insight into the interplay between structural forces and hydrodynamic conditions.
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http://dx.doi.org/10.1016/j.jcis.2023.11.068 | DOI Listing |
J Phys Chem Lett
January 2025
School of Physics, State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 611731, China.
Ultrashort laser pulses are extensively used for efficient manipulation of interfacial spin injection in two-dimensional van der Waals (vdW) heterostructures. However, physical processes accompanying the photoinduced spin transfer dynamics on the all-semiconductor ferromagnetic vdW heterostructure remain largely unexplored. Here, we present a computational investigation of the femtosecond laser pulse induced purely electron-mediated spin transfer dynamics at a time scale of less than 50 fs in a vdW heterostructure.
View Article and Find Full Text PDFNano Lett
January 2025
Department of Physics, Centre for Materials Science and Nanotechnology, University of Oslo, PO Box 1048 Blindern, N-0316 Oslo, Norway.
Polymorphism determines significant variations in materials' properties by lattice symmetry variation. If they are stacked together into multilayers, polymorphs may work as an alternative approach to the sequential deposition of layers with different chemical compositions. However, selective polymorph crystallization during conventional thin film synthesis is not trivial; changes of temperature or pressure when switching from one polymorph to another during synthesis may cause degradation of the structural quality.
View Article and Find Full Text PDFNano Lett
January 2025
Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
Realizing field-free switching of perpendicular magnetization by spin-orbit torques is crucial for developing advanced magnetic memory and logic devices. However, existing methods often involve complex designs or hybrid approaches, which complicate fabrication and affect device stability and scalability. Here, we propose a novel approach using -polarized spin currents for deterministic switching of perpendicular magnetization through interfacial engineering.
View Article and Find Full Text PDFACS Nano
January 2025
IBM Research Europe─Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland.
Highly ordered nanocrystal (NC) assemblies, namely, superlattices (SLs), have been investigated as materials for optical and optoelectronic devices due to their unique properties based on interactions among neighboring NCs. In particular, lead halide perovskite NC SLs have attracted significant attention owing to their extraordinary optical characteristics of individual NCs and collective emission processes like superfluorescence (SF). So far, the primary method for preparing perovskite NC SLs has been the drying-mediated self-assembly method, in which the colloidal NCs spontaneously assemble into SLs during solvent evaporation.
View Article and Find Full Text PDFACS Nano
January 2025
School of Information Science and Technology and Department of Optical Science and Engineering and Key Laboratory of Micro and Nano Photonic Structures (MOE), Fudan University, Shanghai 200433, China.
The formation of large polarons resulting from the Fröhlich coupling of photogenerated carriers with the polarized crystal lattice is considered crucial in shaping the outstanding optoelectronic properties in hybrid organic-inorganic perovskite crystals. Until now, the initial polaron dynamics after photoexcitation have remained elusive in the hybrid perovskite system. Here, based on the terahertz time-domain spectroscopy and optical-pump terahertz probe, we access the nature of interplay between photoexcited unbound charge carriers and optical phonons in MAPbBr within the initial 5 ps after excitation and have demonstrated the simultaneous existence of both electron- and hole-polarons, together with the photogenerated carrier dynamic process.
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