We report a high-resolution terahertz spectroscopic study of quantum spin dynamics in the antiferromagnetic Heisenberg-Ising spin-chain compound BaCo_{2}V_{2}O_{8} as a function of temperature and longitudinal magnetic field. Confined spinon excitations are observed in an antiferromagnetic phase below T_{N}≃5.5 K. In a field-induced gapless phase above B_{c}=3.8 T, we identify many-body string excitations as well as low-energy fractional psinon or antipsinon excitations by comparing to Bethe ansatz calculations. In the vicinity of B_{c}, the high-energy string excitations are found to have a dominant contribution to the spin dynamics as compared with the fractional excitations.
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http://dx.doi.org/10.1103/PhysRevLett.123.067202 | DOI Listing |
Acta Neurol Belg
January 2025
Department of Neurology, National Institute of Mental Health & Neurosciences, Bangalore, 560029, India.
Background: Neuromyelitis optica spectrum disorder (NMOSD) is a relapsing central nervous system disease most commonly associated with aquaporin-4 antibodies (AQP4-Ab) and Myelin oligodendrocyte glycoprotein (MOG) antibodies. These demyelinating disorders influence cortical excitability, which has been studied using advanced imaging techniques and transcranial magnetic stimulation (TMS) in our study.
Methods: This is a prospective study of 30 subjects.
J Phys Chem A
January 2025
Departamento de Química, Instituto Tecnológico de Aeronáutica, São José dos Campos, 12228-900 São Paulo, Brazil.
Polycyclic aromatic hydrocarbons (PAHs) exhibit intriguing characteristics that position them as promising candidates for advancements in organic semiconductor technologies. Notably, tetracene finds substantial utility in Electronics due to its application in organic light-emitting diodes (OLEDs) and organic field-effect transistors (OFETs). The strategic introduction of an isoelectronic boron-nitrogen (B,N) pair to replace a carbon-carbon pair in acenes introduces changes in the electronic structure, allowing for the controlled modulation of diradical characteristics.
View Article and Find Full Text PDFEnviron Sci Pollut Res Int
January 2025
Department of Chemistry, College of Science and Engineering, Western Washington University, 516 High Street, Bellingham, WA, 98229, USA.
Fluorescent lifetimes of dissolved organic matter (DOM) and associated physicochemical parameters were measured over 14 months in an estuary in Southern California, USA. Measurements were made on 77 samples from sites near the inlet, mid-estuary, and outlet to maximize the range of physicochemical variables. Time-resolved fluorescence data were well fit to a triexponential model with an intermediate lifetime component (τ: 1 to 5 ns), a long lifetime component (τ: 2 to 15 ns), and a short lifetime component (τ: < 1 ns).
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Department of Physics, 104 Davey Lab, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
A fundamental manifestation of the nontrivial correlations of an incompressible fractional quantum Hall (FQH) state is that an electron added to it disintegrates into more elementary particles, namely fractionally-charged composite fermions (CFs). We show here that the Girvin-MacDonald-Platzman (GMP) density-wave excitation of the ν=n/(2pn±1) FQH states also splits into more elementary single CF excitons. In particular, the GMP graviton, which refers to the recently observed spin-2 neutral excitation in the vanishing wave vector limit [Liang et al.
View Article and Find Full Text PDFPhys Rev E
November 2024
Institute of Physics, University of Opole, Oleska 48, 45-052 Opole, Poland.
We study the effects of disorder on the exciton spectra in quantum well (QW) semiconductor structures. We model the disorder by introducing the fractional Laplacian into the Schrödinger equations, which describe the exciton spectra of the above QW structures. We calculate the exciton binding energies in its ground state and a few low-lying excited states as a function of the GaAs QW size.
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