Unidirectional spin-Hall and Rashba−Edelstein magnetoresistance in topological insulator-ferromagnet layer heterostructures

Invited

Abstract

The large spin−orbit coupling in topological insulators results in helical spin-textured Dirac surface states that are attractive for topological spintronics. These states generate an efficient spin−orbit torque on proximal magnetic moments. However, memory or logic spin devices based upon such switching require a non-optimal three-terminal geometry, with two terminals for the writing current and one for reading the state of the device. An alternative two-terminal device geometry is now possible by exploiting the recent discovery of the unidirectional spin Hall magnetoresistance in heavy metal/ferromagnet bilayers and unidirectional magnetoresistance in magnetic topological insulators. Here, we report the observation of such unidirectional magnetoresistance in a technologically relevant device geometry that combines a topological insulator with a conventional ferromagnetic metal. Our devices show a figure of merit (magnetoresistance per current density per total resistance) that is more than twice as large as the highest reported values in all-metal Ta/Co bilayers.

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Presenters

  • Yang Lv

    University of Minnesota, Electrical and Computer Engineering, University of Minnesota

Authors

  • Yang Lv

    University of Minnesota, Electrical and Computer Engineering, University of Minnesota

  • James Kally

    Department of Physics, The Pennsylvania State University

  • Delin Zhang

    Electrical and Computer Engineering, University of Minnesota

  • Joon Sue Lee

    University of California - Santa Barbara, University of California Santa Barbara, Dept. of ECE, University of California Santa Barbara, California NanoSystems Institute, University of California, Santa Barbara, Department of Physics, The Pennsylvania State University, University of California, Santa Barbara

  • Mahdi Jamali

    University of Minnesota, Electrical and Computer Engineering, University of Minnesota

  • Nitin Samarth

    Department of Physics and Materials Research Institute, Pennsylvania State University, Physics, Penn State University, Physics, The Pennsylvania State University, Pennsylvania State University, Department of Physics, Pennsylvania State University, Materials Research Institute, Pennsylvania State University, Department of Physics, The Pennsylvania State University, Physics, Pennsylvania State University

  • Jianping Wang

    University of Minnesota, School of Physics and Astronomy, University of Minnesota, Electrical and Computer Engineering, University of Minnesota