Synthesis of L10 FeNi thin films via High Speed Rapid Thermal Annealing

ORAL

Abstract

High magnetic anisotropy materials are critical for future ultrahigh density magnetic recording and permanent magnet technologies, particularly those that are rare-earth-free and precious-metal-free. Alloys of FeNi can form a metastable high anisotropy $L$1$_{\mathrm{0}}$ phase, but convenient methods of achieving the $L$1$_{\mathrm{0}}$ ordering have remained elusive. Here we report the synthesis of high-anisotropy $L$1$_{\mathrm{0}}$-Fe$_{\mathrm{50}}$Ni$_{\mathrm{50}}$ alloys via sputtering of alternating atomic layers of Fe and Ni, followed by a high speed rapid thermal annealing (RTA). Compared to as grown FeNi (4nm) films that are magnetically soft, RTA treated samples exhibit substantial increases of coercivity by 1-2 orders of magnitude. Magnetization reversal characteristics analyzed by the first-order reversal curve (FORC) technique show the emergence of a new high-anisotropy phase after RTA, and a phase fraction is extracted. Microstructure analysis by electron diffraction reveals a corresponding appearance of previously forbidden diffractions, consistent with the $L$1$_{\mathrm{0}}$ ordering. These results demonstrate a convenient approach to achieve high-anisotropy $L$1$_{\mathrm{0}}$-FeNi.

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Authors

  • Julius De Rojas

    Univ of California - Davis

  • Ethan Anderes

    UC Davis, Lawrence Berkeley National Lab - ALS, National Institute of Standards and Technology - NCNR, Univ of California - Davis, University of California, Davis, California State University, Long Beach, University of California, Irvine, University of California, Merced, UC Merced, U Central Florida, Paul Scherrer Institute, Paul Scherrer Institute in Switzerland, Hartnell Comm Coll, University of Michigan, University of Nevada, Reno, National Security Technologies LLC, Livermore, California, Humboldt State University, Stanford University, San Diego State Univ, Institute of Mathematical Problems of Biology, Eindhoven University of Technology, University Of Nevada Reno, Univ of Nevada - Reno, University of Chicago, Physics Department of the University of Nevada, Reno, NV, USA, Institute for Academic Initiatives, PPC and Graduate School of Engineering, Osaka University, Joint Institute for High Temperatures, PPC and Graduate School of Engineering, Osaka University, Institute for Academic Initiatives, Joint Institute for High Temperatures, National Institute of Standards and Technology, Gaithersburg, MD, Department of Physics, UC Davis, Department of Physics & Astronomy, Univeristy of California Irvine, 92697, Department of Chemistry and of Physics, Univeristy of California Irvine, 92697, Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel 76100, Einstein Centre for Local-Realistic Physics, Cal State Long Beach, University of nevada, Reno, Nicolaus Copernicus University, Torun, Poland, University of Maryland, CERN, Univ of California, Davis

  • Ethan Anderes

    UC Davis, Lawrence Berkeley National Lab - ALS, National Institute of Standards and Technology - NCNR, Univ of California - Davis, University of California, Davis, California State University, Long Beach, University of California, Irvine, University of California, Merced, UC Merced, U Central Florida, Paul Scherrer Institute, Paul Scherrer Institute in Switzerland, Hartnell Comm Coll, University of Michigan, University of Nevada, Reno, National Security Technologies LLC, Livermore, California, Humboldt State University, Stanford University, San Diego State Univ, Institute of Mathematical Problems of Biology, Eindhoven University of Technology, University Of Nevada Reno, Univ of Nevada - Reno, University of Chicago, Physics Department of the University of Nevada, Reno, NV, USA, Institute for Academic Initiatives, PPC and Graduate School of Engineering, Osaka University, Joint Institute for High Temperatures, PPC and Graduate School of Engineering, Osaka University, Institute for Academic Initiatives, Joint Institute for High Temperatures, National Institute of Standards and Technology, Gaithersburg, MD, Department of Physics, UC Davis, Department of Physics & Astronomy, Univeristy of California Irvine, 92697, Department of Chemistry and of Physics, Univeristy of California Irvine, 92697, Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel 76100, Einstein Centre for Local-Realistic Physics, Cal State Long Beach, University of nevada, Reno, Nicolaus Copernicus University, Torun, Poland, University of Maryland, CERN, Univ of California, Davis

  • Ethan Anderes

    UC Davis, Lawrence Berkeley National Lab - ALS, National Institute of Standards and Technology - NCNR, Univ of California - Davis, University of California, Davis, California State University, Long Beach, University of California, Irvine, University of California, Merced, UC Merced, U Central Florida, Paul Scherrer Institute, Paul Scherrer Institute in Switzerland, Hartnell Comm Coll, University of Michigan, University of Nevada, Reno, National Security Technologies LLC, Livermore, California, Humboldt State University, Stanford University, San Diego State Univ, Institute of Mathematical Problems of Biology, Eindhoven University of Technology, University Of Nevada Reno, Univ of Nevada - Reno, University of Chicago, Physics Department of the University of Nevada, Reno, NV, USA, Institute for Academic Initiatives, PPC and Graduate School of Engineering, Osaka University, Joint Institute for High Temperatures, PPC and Graduate School of Engineering, Osaka University, Institute for Academic Initiatives, Joint Institute for High Temperatures, National Institute of Standards and Technology, Gaithersburg, MD, Department of Physics, UC Davis, Department of Physics & Astronomy, Univeristy of California Irvine, 92697, Department of Chemistry and of Physics, Univeristy of California Irvine, 92697, Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel 76100, Einstein Centre for Local-Realistic Physics, Cal State Long Beach, University of nevada, Reno, Nicolaus Copernicus University, Torun, Poland, University of Maryland, CERN, Univ of California, Davis