Calculation of energy barriers for magnetic vortices in sub-100 nm dots

ORAL

Abstract

In a magnetic vortex, the magnetization is curling in plane everywhere except the ``core,'' where it is out of plane. Interest in switching of magnetic vortices in nanodots is stimulated by their potential application for magnetic memories and nano-oscillators. By combining analytical and micromagnetic techniques, we calculated energy barriers for vortex switching in 20 nm-thick iron dots as a function of applied in-plane field and dot diameter. Using analytical formula for magnetization distribution in the vortex,\footnote{N. A. Usov and S. E. Peschany, J. Magn. Magn. Mater. \textbf{118}, 290 (1992).} we performed micromagnetic calculations of the dot energy for different vortex core positions. In contrast to the ``rigid body approximation,'' the core size and core shape in our calculations were varied to achieve the energy minimum for every core displacement. The energy barriers required for vortex nucleation and annihilation were calculated as a function of magnetic field. By comparing these barriers to the thermal energy k$_{\mathrm{B}}$T we obtained the temperature dependences of the vortex nucleation and annihilation fields in good agreement with the experiment.\footnote{R. K. Dumas \textit{et al}., Appl. Phys. Lett. \textbf{91}, 202501 (2007).}

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Authors

  • Pavel Lapa

    Texas A\&M University

  • Iman Rezanejad

    TAMU, TTU, TCU, Texas State University, Department of Physics, Texas Tech University, Lubbock, TX, Department of Chemistry \& Biochemistry, Texas Tech University, Lubbock, TX, Department of Mechanical Engineering, Texas Tech University, Lubbock, TX, Universidade de Sao Paulo, Ohio University, Stanford University, University of Waterloo, Canada, Institute for Quantum Science and Engineering (IQSE) and Department of Physics and Astronomy, Texas A\&M University, Beijing Computational Science Research Center, Beijing, China, Institute for Quantum Studies and Department of Physics, Texas A\&M University, College Station, Texas 77843, USA, Texas A\&M University at Qatar, Education City, P.O. Box 23874, Doha, Qatar, TTU Center for Pulsed Power and Power Electronics, Texas A\&M University - Commerce, Meyer Observatory, Clifton TX, CASPER, Baylor University, Waco TX, CASPER NSF-REU, Baylor University, Waco TX, Texas Tech University, University of Texas at Dallas, Oklahoma University, Princeton University, University of Chicago, Cornell University, Los Alamos National Laboratory, Department of Physics, Lamar University, Department of Physics \& Geosciences, Angelo State University, Brookhaven National Laboratory, Fermi National Accelerator Laboratory, Texas A\&M University, Physics Dept, Texas State University, San Marcos, Istanbul University, Department of Electrical Engineering, University of Texas at Arlington, Department of Physics \& Astronomy, University of Texas at Brownsville, V. N. Bakul Institute for Superhard Materials, University of North Texas, Department of Physics, TCU, Department of Physics and Astronomy, Department of Computer Science, Texas State University at San Marcos, Department of Physics, Texas State University at San Marcos, Institute for Quantum Science and Engineering and Department of Physics and Astronomy, Texas A\&M University, College Station, Texas 77843, USA, The National Center for Mathematics and Physics, KACST, P.O. Box 6086, Riyadh 11442, Saudi Arabia, Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui, 230026, People's Republic of China, Department of Physics, the University of Texas at Dallas, Richardson, TX, 75080 USA, State Key Laboratory of Quantum Optics and Quantum Optics Devices, College of Physics and Electronic Engineering, Shanxi University, Taiyuan 030006, Department of Physics and Astronomy, Washington State University, Pullman, Washington, 99164 USA, University of Guelph, Guelph Canada, Department of Physics, National Chung Cheng University, Chia-Yi 621, Taiwan, University of Houston Clear Lake, The University of Texas at Dallas, The University of Texas at San Antonio, Angelo State University, Department of Physics and Astronomy and Center for Gravitational Wave Astronomy, University of Texas at Brownsville, Brownsville, Texas 78520 USA, Laboratoire des Mat\'eriaux Avanc\'es, Universit\'e Claude Bernard Lyon 1, Campus de la DOUA, Villeurbanne Cedex 69622 France, Department of Engineering, University of Texas at Brownsville, Brownsville, Texas 78520 USA, BAE Systems, Advanced Systems and Technology, Nashua, NH, Istanbul University, Beyazit 3449 Istanbul, Turkey, Texas Tech University, Physics, Texas Tech University, Lubbock, TX, Istanbul University, Istanbul, Turkey, Arkansas State University, Jonesboro, AK, Abilene Christian University, Department of Physics and Astronomy, Clemson University, Clemson, SC, 29634 USA, Department of Physics, University of Texas at El Paso, Qatar Biomedical Research Institute, Texas A\&M University at Qatar, FUTY, Yola, Adamawa State, Nigeria, FUTY, Yola, Adamawa State, Department of Physics, University of Abuja, Abuja, Nigeria, Department of Electrical and Computer Engineering, Texas A\&M University

  • Iman Rezanejad

    TAMU, TTU, TCU, Texas State University, Department of Physics, Texas Tech University, Lubbock, TX, Department of Chemistry \& Biochemistry, Texas Tech University, Lubbock, TX, Department of Mechanical Engineering, Texas Tech University, Lubbock, TX, Universidade de Sao Paulo, Ohio University, Stanford University, University of Waterloo, Canada, Institute for Quantum Science and Engineering (IQSE) and Department of Physics and Astronomy, Texas A\&M University, Beijing Computational Science Research Center, Beijing, China, Institute for Quantum Studies and Department of Physics, Texas A\&M University, College Station, Texas 77843, USA, Texas A\&M University at Qatar, Education City, P.O. Box 23874, Doha, Qatar, TTU Center for Pulsed Power and Power Electronics, Texas A\&M University - Commerce, Meyer Observatory, Clifton TX, CASPER, Baylor University, Waco TX, CASPER NSF-REU, Baylor University, Waco TX, Texas Tech University, University of Texas at Dallas, Oklahoma University, Princeton University, University of Chicago, Cornell University, Los Alamos National Laboratory, Department of Physics, Lamar University, Department of Physics \& Geosciences, Angelo State University, Brookhaven National Laboratory, Fermi National Accelerator Laboratory, Texas A\&M University, Physics Dept, Texas State University, San Marcos, Istanbul University, Department of Electrical Engineering, University of Texas at Arlington, Department of Physics \& Astronomy, University of Texas at Brownsville, V. N. Bakul Institute for Superhard Materials, University of North Texas, Department of Physics, TCU, Department of Physics and Astronomy, Department of Computer Science, Texas State University at San Marcos, Department of Physics, Texas State University at San Marcos, Institute for Quantum Science and Engineering and Department of Physics and Astronomy, Texas A\&M University, College Station, Texas 77843, USA, The National Center for Mathematics and Physics, KACST, P.O. Box 6086, Riyadh 11442, Saudi Arabia, Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui, 230026, People's Republic of China, Department of Physics, the University of Texas at Dallas, Richardson, TX, 75080 USA, State Key Laboratory of Quantum Optics and Quantum Optics Devices, College of Physics and Electronic Engineering, Shanxi University, Taiyuan 030006, Department of Physics and Astronomy, Washington State University, Pullman, Washington, 99164 USA, University of Guelph, Guelph Canada, Department of Physics, National Chung Cheng University, Chia-Yi 621, Taiwan, University of Houston Clear Lake, The University of Texas at Dallas, The University of Texas at San Antonio, Angelo State University, Department of Physics and Astronomy and Center for Gravitational Wave Astronomy, University of Texas at Brownsville, Brownsville, Texas 78520 USA, Laboratoire des Mat\'eriaux Avanc\'es, Universit\'e Claude Bernard Lyon 1, Campus de la DOUA, Villeurbanne Cedex 69622 France, Department of Engineering, University of Texas at Brownsville, Brownsville, Texas 78520 USA, BAE Systems, Advanced Systems and Technology, Nashua, NH, Istanbul University, Beyazit 3449 Istanbul, Turkey, Texas Tech University, Physics, Texas Tech University, Lubbock, TX, Istanbul University, Istanbul, Turkey, Arkansas State University, Jonesboro, AK, Abilene Christian University, Department of Physics and Astronomy, Clemson University, Clemson, SC, 29634 USA, Department of Physics, University of Texas at El Paso, Qatar Biomedical Research Institute, Texas A\&M University at Qatar, FUTY, Yola, Adamawa State, Nigeria, FUTY, Yola, Adamawa State, Department of Physics, University of Abuja, Abuja, Nigeria, Department of Electrical and Computer Engineering, Texas A\&M University