Spin-transfer-torque reversal in perpendicular anisotropy spin valves with composite free layers

Yulaev, I.; Lubarda, Marko V.; Mangin, Stéphane; Lomakin, Vitaliy; Fullerton, Eric E.

doi:10.1063/1.3643046

Cited by 32 publications

(19 citation statements)

References 22 publications

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“…Spin-torque nano oscillators based on synthetic antiferromagnets have been proposed theoretically [9,10]. In addition, spin-transfer-torque driven magnetic structures comprising high and low magnetic anisotropy materials have been theoretically analyzed [11,12] and experimentally investigated [13][14][15]. These studies verified that the critical switching current of ferromagnetically coupled magnetic bilayers can be reduced significantly.…”

Section: Introduction Exchange Coupled Magnetsmentioning

confidence: 62%

Ultrafast Spin-Transfer-Torque Switching of Synthetic Ferrimagnets

et al. 2016

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The switching speed and the write current required for spin-transfer-torque reversal of spintronic devices such as magnetic tunnel junctions (MTJ) currently hinder their wide implementation into memory and logic devices. This problem is further exacerbated as the dimensions of MTJ nanostructures are scaled down to tens of nanometers in diameter, as higher magnetic anisotropy materials are required to meet thermal stability requirements that demand higher switching current densities. Here, we propose a simple solution to these issues based on synthetic ferrimagnet (SFM) structures. It is commonly assumed that to achieve a given switching delay, the current has to exceed the critical current by a certain factor and so a higher critical current implies a higher switching current. We show that this is not the case for SFM structures which can provide significantly reduced switching delay for a given current density, even though the critical current is increased. This non-intuitive result can be understood from the requirements of angular momentum conservation. We conclude that a 20 nm diameter MTJ incorporating the proposed SFM free layer structure can be switched in tens of picosecond time scales. This remarkable switching speed can be attained employing current perpendicular magnetic anisotropy materials with experimentally demonstrated exchange coupling strengths.

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Section: Introduction Exchange Coupled Magnetsmentioning

confidence: 62%

Ultrafast Spin-Transfer-Torque Switching of Synthetic Ferrimagnets

et al. 2016

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“…By controlling U K and optimizing materials properties such as spin polarization and magnetic damping, the critical switching current can be reduced by more than one order of magnitude, while maintaining thermal stability [51,83]. Note that in perpendicular anisotropy structures with composite free layers it should be possible to further decrease the critical switching current while maintaining stability [84].…”

Section: Introductionmentioning

confidence: 99%

State diagram of nanopillar spin valves with perpendicular magnetic anisotropy

et al. 2012

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The spin-torque switching of metallic nanopillar spin-valves showing strong perpendicular anisotropy are studied. The magnetic states of the layers depend on extrinsic parameters such as the magnetic field and the DC current applied to the device. A state diagram presents a comprehensive graph the role of those parameters on the spin-valve magnetic response. After explaining how state diagrams can be built and the different possible representation, experimental state diagram are studied for perpendicular devices and the influence of lateral size, temperature and field orientation are shown. An analytical model of a purely uniaxial system is presented. It is shown that this simple model does not properly reflect the experimental results whereas if the symmetry is broken a qualitative agreement is obtained. Finally the possible origins of the symmetry break are discussed in the light of analytical model and numerical simulations.2

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“…Ferromagnetic coupling provides a pathway to engineer incoherent magnetic reversal that allows a reduction of the magnetic field required to write magnetic recording media and further allows control of inter-granular exchange. 8,[10][11][12] A similar approach has been proposed to lower the write current in spin-transfertorque (STT) MRAM devices 13 and to tune the operating frequencies of planar microwave 14 and spin-torque devices. 15 In this letter, we detail the strong and tunable ferromagnetic interlayer coupling across amorphous paramagnetic Fe-Ta alloys.…”

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confidence: 99%

Paramagnetic FexTa1-x alloys for engineering of perpendicularly magnetized tunnel junctions

et al. 2013

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Exchange coupling between two magnetic layers through an interlayer is of broad interest for numerous recent applications of nano-magnetic systems. In this Letter we study ferromagnetic exchange coupling through amorphous paramagnetic Fe-Ta alloys. We show that the exchange coupling depends exponentially on spacer thickness and scales with the Fe-Ta susceptibility, which can be tuned via the alloy composition and/or temperature. Such materials are of high interest for the engineering of perpendicularly magnetized CoFeB-MgO based tunnel junctions as it enables ferromagnetic coupling of magnetic layers with differing crystalline lattices, suppresses dead layers and can act as an inter-diffusion barrier during annealing.

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Spin-transfer-torque reversal in perpendicular anisotropy spin valves with composite free layers

Abstract: To cite this version:I Yulaev, M Lubarda, S. Mangin, V. Lomakin, Eric Fullerton. Spin-transfer-torque reversal in perpendicular anisotropy spin valves with composite free layers.

Cited by 32 publications

References 22 publications

Ultrafast Spin-Transfer-Torque Switching of Synthetic Ferrimagnets

Ultrafast Spin-Transfer-Torque Switching of Synthetic Ferrimagnets

State diagram of nanopillar spin valves with perpendicular magnetic anisotropy

Paramagnetic FexTa1-x alloys for engineering of perpendicularly magnetized tunnel junctions

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