Transparent ferromagnetic and semiconducting behavior in Fe-Dy-Tb based amorphous oxide films.
We report a class of amorphous thin film material comprising of transition (Fe) and Lanthanide metals (Dy and Tb) that show unique combination of functional properties. Films were deposited with different atomic weight ratio (R) of Fe to Lanthanide (Dy + Tb) using electron beam co-evaporation at room temperature. The films were found to be amorphous, with grazing incidence x-ray diffraction and x-ray photoelectron spectroscopy studies indicating that the films were largely oxidized with a majority of the metal being in higher oxidation states. Films with R = 0.6 were semiconducting with visible light transmission due to a direct optical band-gap (2.49 eV), had low resistivity and sheet resistance (7.15 × 10(-4) Ω-cm and ~200 Ω/sq respectively), and showed room temperature ferromagnetism. A metal to semiconductor transition with composition (for R < 11.9) also correlated well with the absence of any metallic Fe(0) oxidation state in the R = 0.6 case as well as a significantly higher fraction of oxidized Dy. The combination of amorphous microstructure and room temperature electronic and magnetic properties could lead to the use of the material in multiple applications, including as a transparent conductor, active material in thin film transistors for display devices, and in spin-dependent electronics.
Bredesen Center, University of Tennessee, Knoxville, Tennessee 37996, USA.
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Taz
Advanced Materials Processing and Analysis Center (AMPAC), NanoScience Technology Center (NSTC), Materials Science and Engineering (MSE) Department, Orlando, Florida 32816, USA.
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Sakthivel
NSF Engineering Research Center for Revolutionizing Metallic Biomaterials, North Carolina A&T State University, Greensboro, North Carolina 27411, USA.
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Yamoah
Department of Material Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA.
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Carr
NSF Engineering Research Center for Revolutionizing Metallic Biomaterials, North Carolina A&T State University, Greensboro, North Carolina 27411, USA.
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Kumar
Advanced Materials Processing and Analysis Center (AMPAC), NanoScience Technology Center (NSTC), Materials Science and Engineering (MSE) Department, Orlando, Florida 32816, USA.
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Seal
Bredesen Center, University of Tennessee, Knoxville, Tennessee 37996, USA.|Department of Material Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA.|Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee, 37996, USA.
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Kalyanaraman