Recent work on magnetic quantum point contacts (QPCs) was discussed. Complete magnetoresistance loops across Co QPCs as small as a single atom was measured. The remarkable feature of these QPCs is the rapid oscillator...Recent work on magnetic quantum point contacts (QPCs) was discussed. Complete magnetoresistance loops across Co QPCs as small as a single atom was measured. The remarkable feature of these QPCs is the rapid oscillatory decay in magnetoresistance with the increase of contact size. In addition, stepwise or quantum magnetoresistance loops are observed, resulting from varying transmission probability of the available discrete conductance channels because the sample is cycled between the ferromagnetic (F) and antiferromagnetic (AF) aligned states. Quantized conductance combined with spin dependent transmission of electron waves gives rise to a multi-channel system with a quantum domain wall acting as a valve, i.e., a quantum spin-valve. Behavior of a few-atom QPC is built on the behavior of a single-atom QPC and hence the summarization of results as ‘single-atom spintronics’. An evolutionary trace of spin-dependent electron transmission from a single atom to bulk is provided, the requisite hallmarks of artefact-free magnetoresistance is established across a QPC – stepwise or quantum magnetoresistance loops and size dependent oscillatory magnetoresistance.展开更多
Flexible and lightweight thermal insulation materials with hierarchical microstructures are ubiquitous in thermal management and protection systems.Ceramic aerogels promise high-temperature thermal insulation but lack...Flexible and lightweight thermal insulation materials with hierarchical microstructures are ubiquitous in thermal management and protection systems.Ceramic aerogels promise high-temperature thermal insulation but lack mechanical robustness,while the fibrous materials with excellent mechanical elasticity display modest thermal insulation.Here we describe flexible hierarchical superhydrophobic ceramic insulation nanocomposites through the densified architectured hierarchical nanostructures,radiative insulation coating,and interfacial cross-linking among composites.The lightweight flexible ceramic nanocomposites exhibit a density of 0.13 g/cm^(3),high-temperature fire resistance with thermal conductivity of 0.024 W/(m·K),and super-hydrophobicity with the water contact angle of 152°.The mechanical robustness and high-temperature thermal insulation of ceramic nanocomposites,together with its soundproof performance,shed light on the low-cost flexible insulation materials manufacturing with scalability for high-temperature thermal insulation applications under high mechanical loading conditions.展开更多
文摘Recent work on magnetic quantum point contacts (QPCs) was discussed. Complete magnetoresistance loops across Co QPCs as small as a single atom was measured. The remarkable feature of these QPCs is the rapid oscillatory decay in magnetoresistance with the increase of contact size. In addition, stepwise or quantum magnetoresistance loops are observed, resulting from varying transmission probability of the available discrete conductance channels because the sample is cycled between the ferromagnetic (F) and antiferromagnetic (AF) aligned states. Quantized conductance combined with spin dependent transmission of electron waves gives rise to a multi-channel system with a quantum domain wall acting as a valve, i.e., a quantum spin-valve. Behavior of a few-atom QPC is built on the behavior of a single-atom QPC and hence the summarization of results as ‘single-atom spintronics’. An evolutionary trace of spin-dependent electron transmission from a single atom to bulk is provided, the requisite hallmarks of artefact-free magnetoresistance is established across a QPC – stepwise or quantum magnetoresistance loops and size dependent oscillatory magnetoresistance.
基金We gratefully acknowledge support from the U.S.Department of Energy(DOE),Office of Energy Efficiency and Renewable Energy(EERE)under the Building Technology Office(BTO)Award(No.DE-EE0008675).
文摘Flexible and lightweight thermal insulation materials with hierarchical microstructures are ubiquitous in thermal management and protection systems.Ceramic aerogels promise high-temperature thermal insulation but lack mechanical robustness,while the fibrous materials with excellent mechanical elasticity display modest thermal insulation.Here we describe flexible hierarchical superhydrophobic ceramic insulation nanocomposites through the densified architectured hierarchical nanostructures,radiative insulation coating,and interfacial cross-linking among composites.The lightweight flexible ceramic nanocomposites exhibit a density of 0.13 g/cm^(3),high-temperature fire resistance with thermal conductivity of 0.024 W/(m·K),and super-hydrophobicity with the water contact angle of 152°.The mechanical robustness and high-temperature thermal insulation of ceramic nanocomposites,together with its soundproof performance,shed light on the low-cost flexible insulation materials manufacturing with scalability for high-temperature thermal insulation applications under high mechanical loading conditions.
