Reversible and irreversible current induced domain wall motion in CoFeB based spin valves stripes

Laribi, Sana; Cros, Vincent; Muñoz, M. C.; Grollier, Julie; Hamzić, Amir; Deranlot, C.; Fert, A.; Martínez, Eduardo; López-Dı́az, L.; Vila, Laurent; Faini, G.; Zoll, S.; Fournel, R.

doi:10.1063/1.2746952

Cited by 32 publications

(31 citation statements)

References 28 publications

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“…Since the prediction of spin-torque effects 2 , many experimental 3,4,5,6,7,8,9,10,11,12,13,14,15 and theoretical 16,17,18 works have been dedicated to the study of currentinduced domain wall motion (CIDM). Besides fundamental investigations, the use of domain walls in logic 19 and memory 20 devices has already been proposed.…”

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confidence: 99%

High Domain Wall Velocity at Zero Magnetic Field Induced by Low Current Densities in Spin Valve Nanostripes

Pizzini

Uhlíř

Vogel

et al. 2009

Appl. Phys. Express

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Current-induced magnetic domain wall motion at zero magnetic field is observed in the permalloy layer of a spin-valve-based nanostripe using photoemission electron microscopy. The domain wall movement is hampered by pinning sites, but in between them high domain wall velocities (exceeding 150 m/s) are obtained for current densities well below 10 12 A/m 2 , suggesting that these trilayer systems are promising for applications in domain wall devices in case of well controlled pinning positions. Vertical spin currents in these structures provide a potential explanation for the increase in domain wall velocity at low current densities.Moving magnetic domain walls using electric currents via spin-torque effects rather than using a magnetic field is one of the recent exciting developments in spintronics 1 . Since the prediction of spin-torque effects 2 , many experimental 3,4,5,6,7,8,9,10,11,12,13,14,15 and theoretical 16,17,18 works have been dedicated to the study of currentinduced domain wall motion (CIDM). Besides fundamental investigations, the use of domain walls in logic 19 and memory 20 devices has already been proposed. Low current densities and high domain wall (DW) velocities at zero magnetic field are required for future applications.Direct evidence of CIDM at zero field has been reported for several nanostripe systems, including permalloy (FeNi) 6,11 , magnetic semiconductors 9 and systems with perpendicular magnetization 7,12,14,15 . For the commonly used FeNi system, the critical current densities are not much below 10 12 A/m 2 at zero magnetic field 8,11 , associated with DW velocities going from some m/s up to about 100 m/s 11 . Much lower critical currents are found for magnetic semiconductors like GaMnAs (about 1 × 10 9 A/m 2 ) because of the low magnetic moments, but the observed DW velocities are small (< 1 m/s) 9 . Moreover, these materials are not ferromagnetic at room temperature. Low current density values are also found in spin-valve-based nanostripes with either in-plane 3,10 or perpendicular anisotropy 7 . Additionally, transport measurements in FeNi/Cu/Co trilayers show CIDM induced by subnanosecond current pulses 5 , indirectly indicating high DW velocities in such spin-valve-based systems. In this work, we show that in these systems CIDM at zero magnetic field can take place with high DW velocities (exceeding 150 m/s) at current densities well below 10 12 A/m 2 . These high velocities are observed only in certain regions of the nanostripes, where domain wall pinning is limited. Currents perpendicular to the plane in the vicinity of the DW are probably partly responsible for this increase in efficiency, which makes the trilayer systems possible candidates for spintronic applications based on CIDM if pinning can be controlled.We observed domain wall motion in the FeNi layer of 400 nm wide FeNi (5 nm)/Cu (8 nm)/Co (7 nm)/ CoO (3 nm) nanostripes, by using Photoemission Electron Microscopy (PEEM) combined with X-ray Magnetic Circular Dichroism (XMCD) 21 . The Cu spacer layer is chosen to ...

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mentioning

confidence: 99%

High Domain Wall Velocity at Zero Magnetic Field Induced by Low Current Densities in Spin Valve Nanostripes

Pizzini

Uhlíř

Vogel

et al. 2009

Appl. Phys. Express

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“…Earlier results on critical current densities found in Co/ Cu/ CoFeB multilayers are significantly smaller than our results. 15 However, the results are difficult to compare directly since critical fields and currents tend to be smaller in multilayer structures.…”

Section: Discussionmentioning

confidence: 99%

“…If the critical current density is governed by the interplay between the adiabatic torque term and the anisotropy, 14 the transverse anisotropy and the damping constant can be engineered to reduce the critical current density j c . 15 In the case of extrinsic pinning at defects such as edge irregularities and grain boundaries intrinsic to the material, the critical current density was found to scale with the critical fields for wall displacement, which manifests itself for instance in an inverse scaling behavior of j crit versus the wire width 16 as well as the critical field for field-induced displacement H crit . 17 Smaller coercive fields than in the usually used Permalloy ͑Ni 80 Fe 20 ͒ have been measured for CoFeB and, recently, very low critical current densities have been observed for current-induced domain wall motion in multilayers made of Co/ Cu/ CoFeB.…”

Section: Introductionmentioning

confidence: 99%

“…17 Smaller coercive fields than in the usually used Permalloy ͑Ni 80 Fe 20 ͒ have been measured for CoFeB and, recently, very low critical current densities have been observed for current-induced domain wall motion in multilayers made of Co/ Cu/ CoFeB. 15 CoFeB that is grown without annealing is known to be amorphous and thus exhibits no grain boundaries where pinning could occur.…”

Section: Introductionmentioning

confidence: 99%

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Direct imaging of current-induced domain wall motion in CoFeB structures

Heyne

Kläui

Backes

et al. 2008

Journal of Applied Physics

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By direct x-ray photoemission electron microscopy imaging, we probe current-induced domain wall motion in 20nm thick CoFeB wires. We observe transverse walls for all wire widths up to 1500nm as a consequence of the small saturation magnetization of the material. High critical current densities above 1×1012A∕m2 for wall displacement due to the spin transfer torque effect are found. The critical current densities jc increase further with decreasing wire width indicating that jc is governed by extrinsic pinning due to edge defects. In addition to wall displacements, we observe wall transformations to energetically favorable wall types due to heating. Owing to the high Curie temperature though, the sample temperature stays below the Curie temperature even for the highest current densities where structural damage sets in.

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“…Despite the attractions of ST devices, their applications are still hampered by the large current density required, which is of the order of 10 6 -10 9 A/cm 2 [9][10][11]. According to theoretical analyses, typical current switching for a ferromagnet (FM) can be significantly reduced if the magnetic layer has a small magnetic moment or exhibits no shape anisotropy [12,13].…”

Section: Introductionmentioning

confidence: 99%