Electro- and magneto-transport properties of amorphous carbon films doped with iron |
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Authors: | Caihua Wan Xiaozhong Zhang Johan VanackenXili Gao Xin Zhang Lihua Wu Xinyu Tan Hong Lin Victor V MoshchalkovJun Yuan |
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Affiliation: | a Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Beijing, 100084, People''s Republic of Chinab INPAC-Institute for Nanoscale Physics and Chemistry, K.U.Leuven, Celestijnenlaan 200 D, B-3001 Leuven, Belgiumc National Center for Electron Microscopy (Beijing), Tsinghua University, Beijing, 100084, People''s Republic of Chinad State Key Laboratory of New Ceramics & Fine Processing, Tsinghua University, Beijing, 100084, People''s Republic of Chinae Department of Physics, University of York, Heslington, York YO10 5DD, UK |
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Abstract: | Electro- and magneto-transport properties of amorphous carbon films doped with iron element have been systematically studied. The electro-transport mechanism of the films is dominated by thermal activation at T > 200 K, Mott-type variable range hopping (VRH) at 200 K > T > 60 K and Efros-Shklovskii type (ES-) VRH at T < 60 K. An anomalous giant positive magnetoresistance (MR) 6.40% is found at the ES-VRH range, which is attributed to the spin blockage effect. At high temperatures, an anomalous Hall effect (AHE) is also found with a large AHE coefficiency 49.6 μΩcm/T. Electron energy loss spectroscopy (EELS) reveals that iron atoms chemically bond with carbon matrix. These iron carbides exist as amorphous nanoparticles with a diameter of 6-12 nm, which is regarded as the origin of the MR and AHE. Besides, the films are p-type conductive at high temperature, which might be related with the iron doping. These properties make iron doped amorphous carbon films applicable in carbon-based solar cells, magnetic sensors or some other multifunctional devices. |
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Keywords: | Amorphous carbon Photovoltaic properties Magnetoresistance Anomalous Hall effect |
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