The Experts below are selected from a list of 16812 Experts worldwide ranked by ideXlab platform

Cewen Nan - One of the best experts on this subject based on the ideXlab platform.

  • full 180 Magnetization Reversal with electric fields
    2015
    Co-Authors: Jianjun Wang, Jinxing Zhang, Long Qing Chen, Cewen Nan
    Abstract:

    Achieving 180° Magnetization Reversal with an electric field rather than a current or magnetic field is a fundamental challenge and represents a technological breakthrough towards new memory cell designs. Here we propose a mesoscale morphological engineering approach to accomplishing full 180° Magnetization Reversals with electric fields by utilizing both the in-plane piezostrains and magnetic shape anisotropy of a multiferroic heterostructure. Using phase-field simulations, we examined a patterned single-domain nanomagnet with four-fold magnetic axis on a ferroelectric layer with electric-field-induced uniaxial strains. We demonstrated that the uniaxial piezostrains, if non-collinear to the magnetic easy axis of the nanomagnet at certain angles, induce two successive, deterministic 90° Magnetization rotations, thereby leading to full 180° Magnetization Reversals.

  • purely electric field driven perpendicular Magnetization Reversal
    2015
    Co-Authors: Tiannan Yang, Jianjun Wang, Jinxing Zhang, Long Qing Chen, Houbing Huang, Cewen Nan
    Abstract:

    If achieved, Magnetization Reversal purely with an electric field has the potential to revolutionize the spintronic devices that currently utilize power-dissipating currents. However, all existing proposals involve the use of a magnetic field. Here we use phase-field simulations to study the piezoelectric and magnetoelectric responses in a three-dimensional multiferroic nanostructure consisting of a perpendicularly magnetized nanomagnet with an in-plane long axis and a juxtaposed ferroelectric nanoisland. For the first time, we demonstrate a full Reversal of perpendicular Magnetization via successive precession and damping, driven purely by a perpendicular electric-field pulse of certain pulse duration across the nanoferroelectric. We discuss the materials selection and size dependence of both nanoferroelctrics and nanomagnets for experimental verification. These results offer new inspiration to the design of spintronic devices that simultaneously possess high density, high thermal stability, and high rel...

  • non volatile 180 Magnetization Reversal by an electric field in multiferroic heterostructures
    2014
    Co-Authors: Sheng Wei Yang, Renci Peng, Jianjun Wang, Long Qing Chen, Tao Jiang, Yu Kuai Liu, Lei Feng, Cewen Nan
    Abstract:

    The deterministic rotation of Magnetization by electric fields is a challenging issue for future low-power spintronics. In a Co/0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 multiferroic heterostructure, piezostrain-mediated, macroscopically maneuverable, and non-volatile Magnetization Reversal without an applied magnetic field is demonstrated. This, combined with the presented phase-field simulations, is of practical relevance for designing prototype devices.

Long Qing Chen - One of the best experts on this subject based on the ideXlab platform.

  • full 180 Magnetization Reversal with electric fields
    2015
    Co-Authors: Jianjun Wang, Jinxing Zhang, Long Qing Chen, Cewen Nan
    Abstract:

    Achieving 180° Magnetization Reversal with an electric field rather than a current or magnetic field is a fundamental challenge and represents a technological breakthrough towards new memory cell designs. Here we propose a mesoscale morphological engineering approach to accomplishing full 180° Magnetization Reversals with electric fields by utilizing both the in-plane piezostrains and magnetic shape anisotropy of a multiferroic heterostructure. Using phase-field simulations, we examined a patterned single-domain nanomagnet with four-fold magnetic axis on a ferroelectric layer with electric-field-induced uniaxial strains. We demonstrated that the uniaxial piezostrains, if non-collinear to the magnetic easy axis of the nanomagnet at certain angles, induce two successive, deterministic 90° Magnetization rotations, thereby leading to full 180° Magnetization Reversals.

  • purely electric field driven perpendicular Magnetization Reversal
    2015
    Co-Authors: Tiannan Yang, Jianjun Wang, Jinxing Zhang, Long Qing Chen, Houbing Huang, Cewen Nan
    Abstract:

    If achieved, Magnetization Reversal purely with an electric field has the potential to revolutionize the spintronic devices that currently utilize power-dissipating currents. However, all existing proposals involve the use of a magnetic field. Here we use phase-field simulations to study the piezoelectric and magnetoelectric responses in a three-dimensional multiferroic nanostructure consisting of a perpendicularly magnetized nanomagnet with an in-plane long axis and a juxtaposed ferroelectric nanoisland. For the first time, we demonstrate a full Reversal of perpendicular Magnetization via successive precession and damping, driven purely by a perpendicular electric-field pulse of certain pulse duration across the nanoferroelectric. We discuss the materials selection and size dependence of both nanoferroelctrics and nanomagnets for experimental verification. These results offer new inspiration to the design of spintronic devices that simultaneously possess high density, high thermal stability, and high rel...

  • non volatile 180 Magnetization Reversal by an electric field in multiferroic heterostructures
    2014
    Co-Authors: Sheng Wei Yang, Renci Peng, Jianjun Wang, Long Qing Chen, Tao Jiang, Yu Kuai Liu, Lei Feng, Cewen Nan
    Abstract:

    The deterministic rotation of Magnetization by electric fields is a challenging issue for future low-power spintronics. In a Co/0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 multiferroic heterostructure, piezostrain-mediated, macroscopically maneuverable, and non-volatile Magnetization Reversal without an applied magnetic field is demonstrated. This, combined with the presented phase-field simulations, is of practical relevance for designing prototype devices.

Stuart S P Parkin - One of the best experts on this subject based on the ideXlab platform.

  • thermally assisted Magnetization Reversal in submicron sized magnetic thin films
    2000
    Co-Authors: R H Koch, G Grinstein, George A Keefe, Philip Louis Trouilloud, W J Gallagher, Stuart S P Parkin
    Abstract:

    We have measured the rate of thermally assisted Magnetization Reversal of submicron-sized magnetic thin films. For fields H just less than the zero-temperature switching field H(C), the probability of Reversal, P(exp)(s)(t), increases for short times t, achieves a maximum value, and then decreases exponentially. Micromagnetic simulations exhibit the same behavior and show that the Reversal proceeds through the annihilation of two domain walls that move from opposite sides of the sample. The behavior of P(exp)(s)(t) can be understood through a simple "energy-ladder" model of thermal activation.

  • minimum field strength in precessional Magnetization Reversal
    1999
    Co-Authors: C H Back, Stuart S P Parkin, D Weller, E L Garwin, Rolf Allenspach, W Weber, H C Siegmann
    Abstract:

    Ultrafast magnetic field pulses as short as 2 picoseconds are able to reverse the Magnetization in thin, in-plane, magnetized cobalt films. The field pulses are applied in the plane of the film, and their direction encompasses all angles with the Magnetization. At a right angle to the Magnetization, maximum torque is exerted on the spins. In this geometry, a precessional Magnetization Reversal can be triggered by fields as small as 184 kiloamperes per meter. Applications in future ultrafast magnetic recording schemes can be foreseen.

  • Magnetization Reversal in micron sized magnetic thin films
    1998
    Co-Authors: R H Koch, Philip Louis Trouilloud, W J Gallagher, J G Deak, David W Abraham, R A Altman, Roy Edwin Scheuerlein, K P Roche, Stuart S P Parkin
    Abstract:

    We have measured and simulated the dynamics of Magnetization Reversal in 5 nm by 0.8 by 1.6 $\ensuremath{\mu}\mathrm{m}$ ${\mathrm{Ni}}_{60}{\mathrm{Fe}}_{40}$ thin films. The films measured form the upper electrode of a spin-polarized tunnel junction so that the Magnetization direction of the film can be probed by measuring the tunneling resistance of the junction. When a magnetic field pulse is applied, the time to switch the film Magnetization changes from greater than 10 ns to less than 500 ps as the pulse amplitude is increased from the coercive field to 10 mT and beyond. We have simulated these transitions using micromagnetic modeling of the exact experimental conditions. The simulations agree well with the experimental measurements.

Stephane Mangin - One of the best experts on this subject based on the ideXlab platform.

  • light induced Magnetization Reversal of high anisotropy tbco alloy films
    2012
    Co-Authors: Sabine Alebrand, Eric E Fullerton, Martin Aeschlimann, D Lacour, Matthias Georg Gottwald, M Hehn, Daniel Steil, Mirko Cinchetti, Stephane Mangin
    Abstract:

    Magnetization Reversal using circularly polarized light provides a new way to control Magnetization without any external magnetic field and has the potential to revolutionize magnetic data storage. However, in order to reach ultra-high density data storage, high anisotropy media providing thermal stability are needed. Here, we evidence all-optical Magnetization switching for different TbxCo1-x ferrimagnetic alloy composition and demonstrate all-optical switching for films with anisotropy fields reaching 6 T corresponding to anisotropy constants of 3x106 ergs/cm3. Optical Magnetization switching is observed only for alloys which compensation temperature can be reached through sample heating.

  • Light-induced Magnetization Reversal of high-anisotropy TbCo alloy films
    2012
    Co-Authors: Sabine Alebrand, Martin Aeschlimann, M Hehn, Daniel Steil, Mirko Cinchetti, Matthias Gottwald, Daniel Lacour, Eric Fullerton, Stephane Mangin
    Abstract:

    Magnetization Reversal using circularly polarized light provides a way to control Magnetization without any external magnetic field and has the potential to revolutionize magnetic data storage. However, in order to reach ultra-high density data storage, high anisotropy media providing thermal stability are needed. Here, we evidence all-optical Magnetization switching for different TbxCo1−x ferrimagnetic alloy compositions using fs- and ps-laser pulses and demonstrate all-optical switching for films with anisotropy fields reaching 6 T corresponding to anisotropy constants of 3 × 106 ergs/cm3. Optical Magnetization switching is observed only for alloy compositions where the compensation temperature can be reached through sample heating.

Hideo Ohno - One of the best experts on this subject based on the ideXlab platform.

  • coherent Magnetization Reversal of a cylindrical nanomagnet in shape anisotropy magnetic tunnel junctions
    2021
    Co-Authors: Butsurin Jinnai, Junta Igarashi, Kyota Watanabe, Eli Christopher I Enobio, Shunsuke Fukami, Hideo Ohno
    Abstract:

    A shape-anisotropy magnetic tunnel junction (MTJ) holds promise for its scaling into single-digit nanometers while possessing high data-retention capability. Understanding Magnetization Reversal mode is crucial to quantify the thermal stability factor Δ for data retention with high accuracy. Here, we study Magnetization Reversal mode in the shape-anisotropy MTJ with a 15-nm-thick CoFeB layer by evaluating Δ from two different methods: switching probability and retention time measurements. We find that Magnetization Reversal coherently proceeds in the 15-nm-thick and X/1X-nm-diameter cylindrical nanomagnet in the shape-anisotropy MTJs, in contrast to the conventional interfacial-anisotropy MTJs with a smaller thickness and larger diameter. The coherent Magnetization Reversal of the shape-anisotropy MTJ is also confirmed by astroid curve measurements. This study provides insight into the development of ultrasmall and high-reliability MTJ devices.

  • electric field induced Magnetization Reversal in a perpendicular anisotropy cofeb mgo magnetic tunnel junction
    2012
    Co-Authors: Shun Kanai, F Matsukura, M Yamanouchi, Shoji Ikeda, Yoshinobu Nakatani, Hideo Ohno
    Abstract:

    The electric field-induced ∼180° Magnetization Reversal is realized for a sputtered CoFeB/MgO-based magnetic tunnel junction with perpendicular magnetic easy axis in a static external magnetic field. Application of bias voltage with nanoseconds duration results in a temporal change of magnetic easy axis in the free layer CoFeB to in-plane, which induces precessional motion of Magnetization in the free layer. The Magnetization Reversal takes place when the bias voltage pulse duration is adjusted to a half period of the precession. We show that the back and forth Magnetization Reversal can be observed by using successive application of half-period voltage pulses.

  • electrical manipulation of Magnetization Reversal in a ferromagnetic semiconductor
    2003
    Co-Authors: Daichi Chiba, Michihiko Yamanouchi, F Matsukura, Hideo Ohno
    Abstract:

    We report electrical manipulation of Magnetization processes in a ferromagnetic semiconductor, in which low-density carriers are responsible for the ferromagnetic interaction. The coercive force HC at which Magnetization Reversal occurs can be manipulated by modifying the carrier density through application of electric fields in a gated structure. Electrically assisted Magnetization Reversal, as well as electrical deMagnetization, has been demonstrated through the effect. This electrical manipulation offers a functionality not previously accessible in magnetic materials and may become useful for reversing Magnetization of nanoscale bits for ultrahigh-density information storage.