The spin-dependent transport properties of armchair graphene nanoribbons in the presence of extrinsic spin-orbit coupling induced by a random distribution of nickel adatoms is studied. By combining a recursive Green's function formalism with density functional theory, we explore the influence of ribbon length and metal adatom concentration on the conductance. At a given length, we observed a significant enhancement of the spin-flip channel around resonances and at energies right above the Fermi level. We also estimate the spin-relaxation length, finding values on the order of tens of micrometers at low Ni adatom concentrations. This study is conducted at singular ribbon lengths entirely from fully ab initio methods, providing indirectly evidence that the Dyakonov-Perel spin relaxation mechanism might be the dominant at low concentrations as well as the observation of oscillations in the spin-polarization.
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J Magn Reson
December 2024
Department of Medicine, University of Alberta, Canada; Department of Biochemistry, University of Alberta, Canada. Electronic address:
Solution NMR studies of large systems are hampered by rapid signal decay. We hereby introduce ROCSY (relaxation-optimized total correlation spectroscopy), which maximizes transfer efficiency across J-coupling-connected spin networks by minimizing the amount of time magnetization spends in the transverse plane. Hard pulses are substituted into the Clean-CITY TOCSY pulse element first developed by Ernst and co-workers, allowing for longer delays in which magnetization is aligned along the z-axis.
View Article and Find Full Text PDFAlzheimers Dement
December 2024
Illinois Institute of Technology, Chicago, IL, USA.
Background: Elevated iron in brain is a source of free radicals that causes oxidative stress which has been linked to neuropathologies and cognitive impairment among older adults. The aim of this study was to investigate the association of iron levels with transverse relaxation rate, R, and white matter hyperintensities (WMH), independent of the effects of other metals and age-related neuropathologies.
Method: Cerebral hemispheres from 437 older adults participating in the Rush Memory and Aging Project study (Table 1) were imaged ex-vivo using 3T MRI scanners.
Proc Natl Acad Sci U S A
January 2025
William H. Miller III Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218.
Introducing an experimental technique of time-resolved inelastic neutron scattering (TRINS), we explore the time-dependent effects of resonant pulsed microwaves on the molecular magnet CrFPiv. The octagonal rings of magnetic Cr atoms with antiferromagnetic interactions form a singlet ground state with a weakly split triplet of excitations at 0.8 meV.
View Article and Find Full Text PDFAcc Chem Res
January 2025
Department of Chemistry, Seoul National University, Seoul 151-747, South Korea.
ConspectusWhile traditional quantum chemical theories have long been central to research, they encounter limitations when applied to complex situations. Two of the most widely used quantum chemical approaches, Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TDDFT), perform well in cases with relatively weak electron correlation, such as the ground-state minima of closed-shell systems (Franck-Condon region). However, their applicability diminishes in more demanding scenarios.
View Article and Find Full Text PDFNat Commun
December 2024
Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China.
Spin-polarized lasers have demonstrated many superiorities over conventional lasers in both performance and functionalities. Hybrid organic-inorganic perovskites are emerging spintronic materials with great potential for advancing spin-polarized laser technology. However, the rapid carrier spin relaxation process in hybrid perovskites presents a major bottleneck for spin-polarized lasing.
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