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Structured light with engineered polarization singularities (PSs) provides unprecedented control over spin and orbital angular momentum (SAM/OAM) densities; however, conventional PSs often exhibit limited spatial complexity for advanced light-matter interactions. We propose Mandelbrot fractal polarization singularities (MFPSs) - a novel class of structured light that leverages multifractal geometry to tailor the angular momentum density. Through a robust common-path interferometric strategy employing spatially modulated fractal phase encoding, we experimentally generated MFPSs with hierarchical polarization singularities. We characterized their non-uniform SAM/OAM separation in the focal region. Crucially, the fractal-driven non-uniform angular momentum density enables optical manipulation surpassing conventional singular beams. The selective directional transport and configurable multi-particle trapping of microparticles via tailored angular momentum landscapes were realized. These results not only establish MFPSs as a versatile platform for angular momentum engineering but also bridge singular optics with optical micromanipulation, offering promising solutions for further studies of light-matter interactions.
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http://dx.doi.org/10.1364/OE.563450 | DOI Listing |
Nature
September 2025
National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, USA.
Controlling spin currents, that is, the flow of spin angular momentum, in small magnetic devices, is the principal objective of spin electronics, a main contender for future energy-efficient information technologies. A pure spin current has never been measured directly because the associated electric stray fields and/or shifts in the non-equilibrium spin-dependent distribution functions are too small for conventional experimental detection methods optimized for charge transport. Here we report that resonant inelastic X-ray scattering (RIXS) can bridge this gap by measuring the spin current carried by magnons-the quanta of the spin wave excitations of the magnetic order-in the presence of temperature gradients across a magnetic insulator.
View Article and Find Full Text PDFJ Phys Condens Matter
September 2025
Department of Physics and Astronomy and Center for Materials Research and Analysis, University of Nebraska-Lincoln, Jorgensen Hall, 855 North 16th Str., NE 68588-0299, Lincoln, Nebraska, 68588-0007, UNITED STATES.
The band structure of ultrathin Pd(111) thin films grown on the CrO(0001) surface was studied by angular-resolved photoemission spectroscopy (ARPES) combined with first-principles calculations. The CrO(0001) interface and the expanded Pd lattice constant appears to significantly affect the occupied band structure of an ultrathin palladium film. A characteristic band splitting is seen in the experimental occupied electronic structure, forming a hexagonal pattern approximately half-way from the Γ" point to the surface Brillouin zone boundary.
View Article and Find Full Text PDFPhys Rev Lett
August 2025
Duke University, Thomas Lord Department of Mechanical Engineering and Materials Science, Durham, North Carolina 27708, USA.
Chiral phonons, which are characterized by rotational atomic motion, offer a unique mechanism for transferring angular momentum from phonons to electron spins and other angular momentum carriers. In this Letter, we present a theoretical investigation into the emergence of chiral phonons in a chiral hybrid organic-inorganic perovskite (HOIP) and their critical roles in rigid-body rotation, magnetic moment generation, and spin transport under nonthermal equilibrium conditions. We demonstrate that phonon angular momentum can modify the spin chemical potential via a proposed microscopic Barnett effect, leading to a spatially varying spin chemical potential at the metal/HOIP interface, which subsequently induces spin currents in an adjacent Cu layer, with a magnitude consistent with experimental observations.
View Article and Find Full Text PDFJ Phys Chem A
September 2025
Univ. Rennes, CNRS, IPR (Institut de Physique de Rennes), UMR 6251, Rennes F-35000, France.
We present the first dataset of collisional (de)-excitation rate coefficients of HCN induced by CO, one of the main perturbing gases in cometary atmospheres. The dataset spans the temperature range of 5-50 K. It includes both state-to-state rate coefficients involving the lowest ten and nine rotational levels of HCN and CO, respectively, and the so-called "thermalized" rate coefficients over the rotational population of CO at each kinetic temperature.
View Article and Find Full Text PDFAnn Biomed Eng
September 2025
Department of Training and Movement Sciences, Humboldt-Universität zu Berlin, Philippstr. 13, Haus 11, 10115, Berlin, Germany.
The functional interaction of regulatory mechanisms that manage total centre of mass (CoM) energy, frontal plane whole-body angular momentum and mediolateral margin of stability (MoS) during hole negotiation gait was investigated. Joint kinematics, leg posture, total CoM energy, frontal plane whole-body angular momentum, mediolateral MoS and muscle activation patterns of seven bilateral lower leg muscles were assessed in 18 participants. During hole negotiation, we found an increase in the peak-to-peak range of total CoM energy and frontal plane whole-body angular momentum during the preparation, hole and recovery steps, and a decrease in mediolateral MoS at touch-down during the preparation and hole steps compared to level walking, providing evidence of an increased challenge in stability control.
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