Size dependence of the magnetic response of graphite oxide and graphene flakes - an electron spin resonance study

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Layered oxyselenides are of interest as promising mid-to high-temperature thermoelectric applications due to their tunable electrical properties and intrinsically low lattice thermal conductivity (κ). Understanding microscopic phonon mechanisms driving low-κ in these materials is essential for rational design. Here, we report a layer-differentiated phonon transport in Na 2 CoSe 2 O via solving the Wigner transport equation based on first-principles calculations, where CoSe 6 and Na 6 O octahedra dominate ac

Crude oil shale, an abundant yet underutilized carbon-rich resource with kerogen concentration typically ranging from 20 to 80%, offers significant potential as a feedstock for clean and advanced energy application. Herein, we report an efficient strategy to convert crude oil shale into high-value graphitic carbon materials for lithium-ion battery anodes while simultaneously generating hydrogen-rich gas. The approach utilizes a multistage process, including leaching, supercritical extraction, solid–liquid e

Oxidation of graphene has been successfully used to incorporate semiquinone (C=O)-functionalized Å-scale pores, yielding attractive carbon capture performance. However, the true potential of such pores has remained unclear due to a lack of dedicated mechanistic studies. Herein, using molecular dynamics (MD) simulations, we show that C=O displays a remarkable molecular-interaction-dependent dynamic motion, leading to a distribution in PLD comparable to the size differences between CO2, O2, and N2. Dynamic op

The rapid growth of edge computing, wearable electronics, and Internet-of-Things (IoT) applications is driving demand for microsystems that can locally perform data processing, storage, and intelligent decision-making. These systems must be compact, energy-efficient, and capable of integrating multiple functions within strict area and power constraints . Conventional architectures that physically separate energy storage, memory, and logic increasingly face limitations in footprint, latency, and efficiency.

We have combined magneto-optical Kerr effect, scanning tunneling microscopy, and x-ray magnetic circular dichroism to study the magnetic properties and the morphology of Fe nanoparticles grown on 2 ML thick Al2O3/Ni3Al(111)-(root 67 x root 67)R12.2 degrees with and without Pd seeding. The Ni3Al(111) substrate is ferromagnetic and shows two transition temperatures. The first, T-C1 = 81 +/- 3 K, is attributed to a 20-30 nm thick slightly Ni enriched region; the second, T-C2 = 240 +/- 12 K, is attributed to a

We report on a combined experimental and theoretical investigation of the magnetic anisotropy of Fe and Co ultrathin layers on strongly polarizable metal substrates. Monolayer (ML) films of Co and Fe on Rh(111) have been investigated in situ by x-ray magnetic circular dichroism (XMCD), magneto-optic Kerr effect, and scanning tunneling microscopy. The experiments show that both magnetic adlayers exhibit ferromagnetic order and enhanced spin and orbital moments compared to the bulk metals. The easy magnetizat

The chapter “Magnetism of low-dimensional metallic structures” reviews experiments on the magnetism of surface-supported low-dimensional structures of 3d metals. Controlling the static and dynamic magnetic behavior of both individual impurities and supported nanostructures on nonmagnetic surfaces represents a fundamental challenge as well as a prerequisite to design magnetic storage and logic devices of novel conception. We describe the governing principles of self-organized growth of metallic nanostructure

Microcavity exciton polaritons, the fundamental optical excitations of semiconductor microcavities with quantum wells inside, have been proposed as promising candidates for observing stimulated scattering, condensation and other phenomena related to the bosonic nature of excitons. Having a light mass, quantum degeneracy of polaritons can be reached at low densities and high temperatures. But the radiative time of polaritons is very short (in the picosecond range) and usually prevents an efficient thermaliza

We have measured the giant magnetoimpedance (GMI) of microstructured Co-based Metglas (R) 2714a amorphous magnetic ribbons. Before micropatterning, the amorphous ribbons were chemically thinned or polished, to study the influence of sample thickness and surface state on the GMI effect. The magnetic domain structure of polished foils near saturation is observed using the bitter fluid technique. The well-defined geometry of the samples allows a quantitative comparison of the GMI effect with a simple skin dept

Mono and multifilamentary HTS tapes exhibit non-negligible AC loss in self-field and considerably higher losses in the presence of external magnetic field. The effect of the conductor’s geometry on the AC loss has been investigated in this paper. The nonlinear electromagnetic properties of the superconducting material are expressed with a B-dependent E-J power law and are implemented in Finite Element Method commercial software. The critical current density and the power index n dependence on B are obtained

To understand the behavior of many NMR expts., it is important to det. the spatial distribution of the B1 field. In this paper, we show how this distribution can be mapped independently of spin d., coil responsiveness, and nonlinearities of the B0 field gradients. As a byproduct we obtain a map of the (possibly nonlinear) spatial variation of the B0 field gradients used in the imaging procedure. (c) 1999 Academic Press. [on SciFinder (R)]

It is shown by theory and expt. how coherent superpositions of quantum states in 3-level systems can be manipulated by irradiating 2 connected transitions with 2 resonant fields with suitably shaped time-dependent amplitudes and phases. Three variants are discussed; (i) adiabatic coherence transfer (ACT) between 2 transitions, which may be either allowed or forbidden; (ii) nonadiabatic transfer of coherence to a nonirradiated transition by controlled violation of adiabaticity (CVA); (iii) coherence transfer

The π-electron ring current magnetic susceptibilities and endohedral chemical shifts of the fullerenes are calculated with the London theory. The diamagnetism calculated for the fullerenes that have been characterized to date does not show a monotonic increase toward the graphite value. By carrying out calculations on high-symmetry giant fullerenes (Cn) in the size regime 100 < n

The introduction of silver in the intergranular space of YBa2Cu3O7 ceramics improves their normal state electrical and mechanical properties. The authors report a study of such composites of which the grain size was found to increase with the annealing temperature, and goes through a maximum around 20% wt. silver for a constant annealing temperature (1000°C). Moreover, a maximum in the filling factor of YBa2Cu3O7 is found from AC susceptibility measurements for X≃15% wt. of silver, which also correspon

Size dependence of the magnetic response of graphite oxide and graphene flakes - an electron spin resonance study

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Phonon bunching induced strong four-phonon scattering for low lattice thermal conductivity in layered Na2CoSe2O

Oil Shale Upcycling to Battery-Grade Graphitic Carbon with CO2-Free H2 Coproduction

Gated CO2 permeation across dynamic graphene pores

Nanomaterials for Energy Storage and Neuromorphic Electronics: From Supercapacitors to Antiferroelectric 2D-FETs

Interlayer exchange coupling in ordered Fe nanocluster arrays grown on Al2O3/Ni3Al(111)

Magnetic anisotropy of Fe and Co ultrathin films deposited on Rh(111) and Pt(111) substrates: An experimental and first-principles investigation

Magnetism of Low-dimensional Metallic Structures

Polariton amplification in semiconductor microcavities

Giant magnetoimpedance of chemically thinned and polished magnetic amorphous ribbons

Effect of the geometry of HTS on AC loss by using finite element method simulation with B-dependent E-J power law

Mapping the B1 Field Distribution with Nonideal Gradients in a High-Resolution NMR Spectrometer

Coherence transfer in three-level systems: controlled violation of adiabaticity and antiparallel double resonant irradiation

Magnetism of Carbon Clusters

Magnetic and transport properties of superconducting (YBa2Cu3O7-δ)1-xAgx ceramics