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We show that magnetization reversal in spin-injection devices can be significantly faster when using a chirped r.f. rather than d.c current pulse. Alternatively one can use a simple sinusoidal r.f. pulse or an optimized series of…

Materials Science · Physics 2009-11-11 K. Rivkin , J. B. Ketterson

We report the experimental observation of spin-orbit torque induced switching of perpendicularly magnetized Pt/Co elements in a time resolved stroboscopic experiment based on high resolution Kerr microscopy. Magnetization dynamics is…

In this paper, we study the design of pulse sequences for NMR spectroscopy as a problem of time optimal control of the unitary propagator. Radio frequency pulses are used in coherent spectroscopy to implement a unitary transfer of state.…

Quantum Physics · Physics 2009-11-06 Navin Khaneja , Roger Brockett , Steffen Glaser

We demonstrate a quasi ballistic switching of the magnetization in a microscopic mag-neto resistive memory cell. By means of time resolved magneto transport we follow the large angle precession of the free layer magnetization of a spin…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 H. W. Schumacher , C. Chappert , R. C. Sousa , P. P. Freitas , J. Miltat

The optimum condition of the magnetization alignment to maximize the spin torque diode voltage is derived by solving the Landau-Lifshitz-Gilbert equation. We show that the optimized diode voltage can be one order of magnitude larger than…

Mesoscale and Nanoscale Physics · Physics 2013-04-29 Tomohiro Taniguchi , Hiroshi Imamura

We show that ideal memristors - devices whose resistance is proportional to the charge that flows through them - can be realized using spin torque-driven viscous magnetization dynamics. The latter can be accomplished in the spin liquid…

Applied Physics · Physics 2020-06-16 Guanxiong Chen , Sergei Ivanov , Sergei Urazhdin

The asymptotic behavior of switching time as a function of current for a uniaxial macrospin under the effects of both spin-torque and thermal noise is explored analytically by focusing on its diffusive energy space dynamics. The scaling…

Mesoscale and Nanoscale Physics · Physics 2013-11-25 D. Pinna , A. D. Kent , D. L. Stein

Advanced magnetic recording paradigms typically use large temperature changes to drive switching which is detrimental to device longevity, hence finding non-thermal routes is crucial for future applications. By employing atomistic…

Spin-polarized current through an Al nanoparticle in tunnel contact with two ferromagnets is measured as a function of the direction of the applied magnetic field. The nanoparticle filters the spin of injected electrons along a direction…

Mesoscale and Nanoscale Physics · Physics 2008-09-15 F. T. Birk , C. E. Malec , D. Davidovic

Using the local control theory we derive analytical expressions for magnetic field pulses that steer the magnetization of a monodomain magnetic nanoparticle to a predefined state. Finite-temperature full numerical simulations confirm the…

Other Condensed Matter · Physics 2015-05-13 A. Sukhov , J. Berakdar

We consider a reversal of the magnetic moment of a nano-magnet by the fluctuating spin-torque induced by a non-equilibrium current of electron spins. This is an example of the problem of the escape of a particle from a metastable state…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 Yasuhiro Utsumi , Tomohiro Taniguchi

We present a simple and fast method to simulate spin-torque driven magnetisation dynamics in nano-pillar spin-valve structures. The approach is based on the coupling between a spin transport code based on random matrix theory and a…

Mesoscale and Nanoscale Physics · Physics 2017-09-27 Simone Borlenghi , M. R. Mahani , Hans Fangohr , Matteo Franchin , Anna Delin , Jonas Fransson

We present an ultrafast route for a controlled, toggle switching of magnetic vortex cores with ultrashort unipolar magnetic field pulses. The switching process is found to be largely insensitive to extrinsic parameters, like sample size and…

Materials Science · Physics 2007-05-23 R. Hertel , S. Gliga , M. Fähnle , C. M. Schneider

In ferromagnetic trilayers, a spin-orbit-induced spin current can have a spin polarization of which direction is deviated from that for the spin Hall effect. Recently, magnetization switching in ferromagnetic trilayers has been proposed and…

Materials Science · Physics 2020-02-07 Dong-Kyu Lee , Kyung-Jin Lee

We study analytically the precessional switching of the magnetization of a thin macrospin. We analyze its response when subjected to an external field along its in-plane hard axis. We derive the exact trajectories of the magnetization. The…

Strongly Correlated Electrons · Physics 2009-11-10 T. Devolder , C. Chappert

A quantum theory of magnetization dynamics of a nanomagnet as a sequence of scatterings of each electron spin with the macrospin state of the magnetization results in each encounter a probability distribution of the magnetization recoil…

Mesoscale and Nanoscale Physics · Physics 2012-03-30 Yong Wang , L. J. Sham

Fluctuation-induced stochastic magnetization dynamics plays an important role in magnetic recording and writing. Here we propose that the magnetization dynamics can be optimally controlled by the spin current to minimize or maximize the…

Mesoscale and Nanoscale Physics · Physics 2013-06-06 Yong Wang , Fu-Chun Zhang

The dynamical motion of the magnetization plays a key role in the properties of magnetic materials. If the magnetization is initially away from the equilibrium direction in a magnetic nanoparticle, it will precess at a natural frequency…

Mesoscale and Nanoscale Physics · Physics 2015-06-23 M. G. Phelps , K. L. Livesey , A. M. Ferona , R. E. Camley

We report on a theoretical study about the magneto-dipolar coupling and synchronization between two vortex-based spin-torque nano-oscillators. In this work we study the dependence of the coupling efficiency on the relative magnetization…

We report measurements of magnetic switching and steady-state magnetic precession driven by spin-polarized currents in nanoscale magnetic tunnel junctions with low-resistance, < 5 Ohm-micron-squared, barriers. The current densities required…