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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

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NICHTERWITZ, Martin, Shashank HONNALI, Jonas ZEHNER, Sebastian SCHNEIDER, Darius POHL, Sandra SCHIEMENZ, Sebastian T. B. GÖNNENWEIN, Kornelius NIELSCH, Karin LEISTNER, 2020. Control of Positive and Negative Magnetoresistance in Iron Oxide–Iron Nanocomposite Thin Films for Tunable Magnetoelectric Nanodevices. In: ACS Applied Electronic Materials. ACS Publications. 2(8), pp. 2543-2549. eISSN 2637-6113. Available under: doi: 10.1021/acsaelm.0c00448

@article{Nichterwitz2020Contr-52374, title={Control of Positive and Negative Magnetoresistance in Iron Oxide–Iron Nanocomposite Thin Films for Tunable Magnetoelectric Nanodevices}, year={2020}, doi={10.1021/acsaelm.0c00448}, number={8}, volume={2}, journal={ACS Applied Electronic Materials}, pages={2543--2549}, author={Nichterwitz, Martin and Honnali, Shashank and Zehner, Jonas and Schneider, Sebastian and Pohl, Darius and Schiemenz, Sandra and Gönnenwein, Sebastian T. B. and Nielsch, Kornelius and Leistner, Karin} }

Pohl, Darius terms-of-use Honnali, Shashank Pohl, Darius Schiemenz, Sandra Schiemenz, Sandra Schneider, Sebastian Gönnenwein, Sebastian T. B. Zehner, Jonas 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<sub>3</sub>O<sub>4</sub>–Fe nanocomposite regions due to grain boundary oxidation. At the Fe<sub>3</sub>O<sub>4</sub>/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<sub>3</sub>O<sub>4</sub> 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. Control of Positive and Negative Magnetoresistance in Iron Oxide–Iron Nanocomposite Thin Films for Tunable Magnetoelectric Nanodevices 2021-01-13T10:24:32Z Schneider, Sebastian Honnali, Shashank eng Leistner, Karin Nichterwitz, Martin Nielsch, Kornelius 2020 Gönnenwein, Sebastian T. B. Nichterwitz, Martin Nielsch, Kornelius Zehner, Jonas Leistner, Karin 2021-01-13T10:24:32Z

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