Defect-induced, temperature-independent, tunable magnetoresistance of partially fluorinated graphene foam

Sagar, Rizwan Ur Rehman; Shehzad, Khurram; Ali, Amjad; Stadler, Florian J.; Khan, Qasim; Zhao, Jingjing; Wang, Xiaohao

doi:10.1016/j.carbon.2018.11.003

Cited by 26 publications

(8 citation statements)

References 59 publications

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“…The presented tunable MR relies on the combination of a spin-polarized Fe 3 O 4 phase with nanocrystalline iron grains. So far, the introduction of artificial defects, such as vertical grain boundaries in perovskite manganite thin films and crystalline boundaries in graphene, was applied to tune MR in an irreversible manner. In contrast, in the present approach, the locally oxidized regions adjacent to iron are susceptible to voltage-induced reduction processes during electrolytic gating, which enables voltage-tunable MR.…”

Section: Discussionmentioning

confidence: 99%

Control of Positive and Negative Magnetoresistance in Iron Oxide–Iron Nanocomposite Thin Films for Tunable Magnetoelectric Nanodevices

Nichterwitz

Honnali

Zehner

et al. 2020

ACS Appl. Electron. Mater.

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The perspective of energy-efficient and tunable functional magnetic nanostructures has triggered research efforts in the fields of voltage control of magnetism and spintronics. We investigate the magnetotransport properties of nanocomposite iron oxide/iron thin films with a nominal iron thickness of 5−50 nm and find a positive magnetoresistance at small thicknesses. The highest magnetoresistance was found for 30 nm Fe with +1.1% at 3 T. This anomalous behavior is attributed to the presence of Fe 3 O 4 −Fe nanocomposite regions due to grain boundary oxidation. At the Fe 3 O 4 /Fe interfaces, spin-polarized electrons in the magnetite can be scattered and reoriented. A crossover to negative magnetoresistance (−0.11%) is achieved at a larger thickness (>40 nm) when interface scattering effects become negligible as more current flows through the iron layer. Electrolytic gating of this system induces voltage-triggered redox reactions in the Fe 3 O 4 regions and thereby enables voltage-tuning of the magnetoresistance with the locally oxidized regions as the active tuning elements. In the low-magnetic-field region (<1 T), a crossover from positive to negative magnetoresistance is achieved by a voltage change of only 1.72 V. At 3 T, a relative change of magnetoresistance about −45% during reduction was achieved for the 30 nm Fe sample. The present low-voltage approach signifies a step forward to practical and tunable room-temperature magnetoresistance-based nanodevices, which can boost the development of nanoscale and energy-efficient magnetic field sensors with high sensitivity, magnetic memories, and magnetoelectric devices in general.

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Section: Discussionmentioning

confidence: 99%

Control of Positive and Negative Magnetoresistance in Iron Oxide–Iron Nanocomposite Thin Films for Tunable Magnetoelectric Nanodevices

Nichterwitz

Honnali

Zehner

et al. 2020

ACS Appl. Electron. Mater.

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“…Herein, we report the preparation of robust, macroporous three-dimensional (3D) wood structures for wastewater treatment. The native Gb wood is used directly as a template, decorated with palladium nanoparticles (Pd NPs) by embedding the NPs or inserting into the lumen space or into wood cell walls. ,, The Pd NPs have shown excellent catalytic efficiency, where materials are often synthesized on nanoporous supports such as silica, zeolite cages, metal oxides, and carbon to avoid agglomeration . The wood 3D substrate supports the in situ formation of Pd NPs, which is composed of long, irregularly shaped wood channels with varying diameter along the growth direction.…”

Section: Introductionmentioning

confidence: 99%

Life-Cycle Assessment of Gingko-Wood Three-Dimensional Membrane for Wastewater Treatment

et al. 2020

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Forest is one of nature's most generous gifts to human beings, providing materials and shelters for all living beings with over 30% global land coverage. Apart from being sustainable, biodegradable, and renewable, wood is also extremely fascinating from the application aspect, with numerous advantages including hierarchical and macroporous structure, excellent mechanical performance, and versatile chemistry. The macroporous structure of wood is comprised of numerous long, partially aligned channels along the growth direction. This structure is suitable for a range of emerging applications, especially as a separation/membrane material. In this research, the potentiality of Gingko biloba (Gb) wood in the remediation of wastewater, contaminated with methylene blue (MB), a dye found in the industrial waters, was investigated. We report a macroporous, three-dimensional (3D) Gb-wood membrane decorated with palladium nanoparticles (Pd NPs) for efficient wastewater treatment. The efficiency of the Pd NPs/Gbwood membrane to remove MB from a flowing aqueous solution was demonstrated. The wastewater treatment rate of the 3D Pd NPs/Gb-wood membrane can reach 0.5 L/min, with a high MB removal efficiency (>99.9%). The 3D Gb-wood macroporous membrane with partially aligned channels exhibits promising results for water treatment and is applicable for an even wider range of separation applications. In addition, the benefit of this 3D-wood membrane system for wastewater treatment was evaluated against the potential impacts on the environment and human health by employing the life-cycle assessment (LCA) approach. The LCA was carried out using the Gabi-education version with the gate-to-grave approach, including industrial wastewater, 3D-wood membrane, and electricity consumption using CML (Centrum VoorMilieukunde Leiden). From the LCA, it can be observed that wastewater filtration using this membrane exhibited a better environmental footprint due to the improved performance of the membrane in treating a higher volume of the permeate. Therefore, this filtration system had outweighed the additional environmental impact of the wastewater treatment process. The energy demand was identified as the main environmental hotspot in the LCA analysis. The analysis revealed that the energy source for electricity generation had a significant influence on the overall sustainability of this system. Additionally, the wood itself, a naturally abundant and eco-friendly material, presented zero environmental hazard to the environment during the filtration process. The experimental and environmental impact results indicate that Gb-wood can be employed as a natural and eco-friendly adsorbent material for the removal of waste from aqueous solutions.

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“…It is noticeable that the MR versus B curves are merged into a single curve independent of temperature, as shown in the right panel of Figure a. Such TIMR in graphene-based materials was reported in fluorinated graphene foam, which was explained by the use of variable-range hopping in disordered graphene foam. Nevertheless, the observed MR was rather small (below 50% at 5 T), making it problematic that the fluorinated graphene foam was used for a field sensor.…”

Section: Resultsmentioning

confidence: 99%

Large Temperature-Independent Magnetoresistance without Gating Operation in Monolayer Graphene

Jeon

Lee

Kim

et al. 2020

ACS Appl. Mater. Interfaces

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Temperature-independent magnetoresistance (TIMR) has been studied for applications in magnetic field sensors operating in wide temperature ranges. Graphene is considered as one of the best candidates for achieving nonsaturating and large TIMR through engineering disorders. Nevertheless, large TIMR has not been achieved in disordered graphene with intrinsic defects, such as chemical doping and atomic dislocations. In this work, by introducing extrinsic defects, we realize nonsaturating and large TIMR in monolayer graphene transferred on a BiFeO 3 nanoisland array (G/BFO-NIA). Furthermore, the G/BFO-NIA device exhibits a significantly larger MR (∼250% under 9 T) than other materials without gating operation, demonstrating its application feasibility. It is shown that the large MR is a result of the coexistence of electrons and holes with almost the same density, and the observed TIMR originates from the temperature dependence of carrier transport in graphene and of the dielectric property of BFO-NIA.

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Defect-induced, temperature-independent, tunable magnetoresistance of partially fluorinated graphene foam

Cited by 26 publications

References 59 publications

Control of Positive and Negative Magnetoresistance in Iron Oxide–Iron Nanocomposite Thin Films for Tunable Magnetoelectric Nanodevices

Control of Positive and Negative Magnetoresistance in Iron Oxide–Iron Nanocomposite Thin Films for Tunable Magnetoelectric Nanodevices

Life-Cycle Assessment of Gingko-Wood Three-Dimensional Membrane for Wastewater Treatment

Large Temperature-Independent Magnetoresistance without Gating Operation in Monolayer Graphene

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