CNRS Spintronics and Technology of Components

Grenoble, France

CNRS Spintronics and Technology of Components

Grenoble, France
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Onur Avci C.,Catalan Institute of Nanoscience and Nanotechnology | Garello K.,Catalan Institute of Nanoscience and Nanotechnology | Mihai Miron I.,CNRS Spintronics and Technology of Components | Gaudin G.,CNRS Spintronics and Technology of Components | And 5 more authors.
Applied Physics Letters | Year: 2012

We demonstrate magnetization switching of a perpendicularly magnetized MgO/Co/Pt trilayer by application of an in-plane current and a constant in-plane magnetic field of small amplitude. Switching occurs due to an effective torque generated by spin-orbit coupling intrinsic to the trilayer structure. We investigate the dependence of the critical switching current on the current pulse width, showing that magnetization reversal in the dc limit is assisted by thermal fluctuations. © 2012 American Institute of Physics.


Miron I.M.,Catalan Institute of Nanoscience and Nanotechnology | Gaudin G.,CNRS Spintronics and Technology of Components | Auffret S.,CNRS Spintronics and Technology of Components | Rodmacq B.,CNRS Spintronics and Technology of Components | And 5 more authors.
Nature Materials | Year: 2010

Methods to manipulate the magnetization of ferromagnets by means of local electric fields or current-induced spin transfer torque allow the design of integrated spintronic devices with reduced dimensions and energy consumption compared with conventional magnetic field actuation. An alternative way to induce a spin torque using an electric current has been proposed based on intrinsic spin-orbit magnetic fields and recently realized in a strained low-temperature ferromagnetic semiconductor. Here we demonstrate that strong magnetic fields can be induced in ferromagnetic metal films lacking structure inversion symmetry through the Rashba effect. Owing to the combination of spin-orbit and exchange interactions, we show that an electric current flowing in the plane of a Co layer with asymmetric Pt and AlOx interfaces produces an effective transverse magnetic field of 1 T per 108 A cm-2. Besides its fundamental significance, the high efficiency of this process makes it a realistic candidate for room-temperature spintronic applications.


Miron I.M.,CNRS Spintronics and Technology of Components | Miron I.M.,Catalan Institute of Nanoscience and Nanotechnology | Moore T.,CNRS Spintronics and Technology of Components | Moore T.,CNRS Neel Institute | And 10 more authors.
Nature Materials | Year: 2011

The propagation of magnetic domain walls induced by spin-polarized currents has launched new concepts for memory and logic devices. A wave of studies focusing on permalloy (NiFe) nanowires has found evidence for high domain-wall velocities (100 ms-1; refs 10, 11), but has also exposed the drawbacks of this phenomenon for applications. Often the domain-wall displacements are not reproducible, their depinning from a thermally stable position is difficult and the domain-wall structural instability (Walker breakdown) limits the maximum velocity. Here, we show that the combined action of spin-transfer and spin-orbit torques offers a comprehensive solution to these problems. In an ultrathin Co nanowire, integrated in a trilayer with structural inversion asymmetry (SIA), the high spin-torque efficiency facilitates the depinning and leads to high mobility, while the SIA-mediated Rashba field controlling the domain-wall chirality stabilizes the Bloch domain-wall structure. Thus, the high-mobility regime is extended to higher current densities, allowing domain-wall velocities up to 400ms-1. © 2011 Macmillan Publishers Limited. All rights reserved.


Garello K.,Catalan Institute of Nanoscience and Nanotechnology | Miron I.M.,CNRS Spintronics and Technology of Components | Avci C.O.,Catalan Institute of Nanoscience and Nanotechnology | Freimuth F.,Jülich Research Center | And 8 more authors.
Nature Nanotechnology | Year: 2013

Recent demonstrations of magnetization switching induced by in-plane current injection in heavy metal/ferromagnetic heterostructures have drawn increasing attention to spin torques based on orbital-to-spin momentum transfer. The symmetry, magnitude and origin of spin-orbit torques (SOTs), however, remain a matter of debate. Here we report on the three-dimensional vector measurement of SOTs in AlO x/Co/Pt and MgO/CoFeB/Ta trilayers using harmonic analysis of the anomalous and planar Hall effects. We provide a general scheme to measure the amplitude and direction of SOTs as a function of the magnetization direction. Based on space and time inversion symmetry arguments, we demonstrate that heavy metal/ferromagnetic layers allow for two different SOTs having odd and even behaviour with respect to magnetization reversal. Such torques include strongly anisotropic field-like and spin transfer-like components, which depend on the type of heavy metal layer and annealing treatment. These results call for SOT models that go beyond the spin Hall and Rashba effects investigated thus far. © 2013 Macmillan Publishers Limited. All rights reserved.


Cascales J.P.,Autonomous University of Madrid | Herranz D.,Autonomous University of Madrid | Sambricio J.L.,Autonomous University of Madrid | Ebels U.,CNRS Spintronics and Technology of Components | And 2 more authors.
Applied Physics Letters | Year: 2013

We report on room temperature magnetoresistance and low frequency noise in sub-100 nm elliptic CoFeB/MgO/CoFeB magnetic tunnel junctions with ultrathin (0.9 nm) barriers. For magnetic fields applied along the hard axis, we observe current induced magnetization switching between the antiparallel and parallel alignments at dc current densities as low as 4 × 106 A/cm 2. We attribute the low value of the critical current to the influence of localized reductions in the tunnel barrier, which affects the current distribution. The analysis of random telegraph noise, which appears in the field interval near a magnetization switch, provides an estimate to the dimension of the pseudo pinholes that trigger the magnetization switching via local spin torque. Micromagnetic simulations qualitatively and quantitatively reproduce the main experimental observations. © 2013 American Institute of Physics.


Pizzini S.,CNRS Neel Institute | Vogel J.,CNRS Neel Institute | Rohart S.,University Paris - Sud | Buda-Prejbeanu L.D.,CNRS Spintronics and Technology of Components | And 7 more authors.
Physical Review Letters | Year: 2014

The nucleation of reversed magnetic domains in Pt/Co/AlOx microstructures with perpendicular anisotropy was studied experimentally in the presence of an in-plane magnetic field. For large enough in-plane field, nucleation was observed preferentially at an edge of the sample normal to this field. The position at which nucleation takes place was observed to depend in a chiral way on the initial magnetization and applied field directions. A quantitative explanation of these results is proposed, based on the existence of a sizable Dzyaloshinskii-Moriya interaction in this sample. Another consequence of this interaction is that the energy of domain walls can become negative for in-plane fields smaller than the effective anisotropy field. © 2014 American Physical Society.


Thiaville A.,University Paris - Sud | Rohart S.,University Paris - Sud | Jue E.,CNRS Spintronics and Technology of Components | Cros V.,University Paris - Sud | Fert A.,University Paris - Sud
EPL | Year: 2012

We explore a new type of domain wall structure in ultrathin films with perpendicular anisotropy, that is influenced by the Dzyaloshinskii-Moriya interaction due to the adjacent layers. This study is performed by numerical and analytical micromagnetics. We show that these walls can behave like Néel walls with very high stability, moving in stationary conditions at large velocities under large fields. We discuss the relevance of such walls, that we propose to call Dzyaloshinskii domain walls, for current-driven domain wall motion under the spin Hall effect. © Copyright EPLA, 2012.


Cubukcu M.,CNRS Spintronics and Technology of Components | Boulle O.,CNRS Spintronics and Technology of Components | Drouard M.,CNRS Spintronics and Technology of Components | Garello K.,ETH Zurich | And 6 more authors.
Applied Physics Letters | Year: 2014

We report on the current-induced magnetization switching of a three-terminal perpendicular magnetic tunnel junction by spin-orbit torque and its read-out using the tunnelling magnetoresistance (TMR) effect. The device is composed of a perpendicular Ta/FeCoB/MgO/FeCoB stack on top of a Ta current line. The magnetization of the bottom FeCoB layer can be switched reproducibly by the injection of current pulses with density 5×1011A/m2 in the Ta layer in the presence of an in-plane bias magnetic field, leading to the full-scale change of the TMR signal. Our work demonstrates the proof of concept of a perpendicular spin-orbit torque magnetic memory cell. © 2014 AIP Publishing LLC.


Kalitsov A.,University of Puerto Rico at San Juan | Silvestre W.,University of Puerto Rico at San Juan | Chshiev M.,CNRS Spintronics and Technology of Components | Velev J.P.,University of Puerto Rico at San Juan | And 2 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

We derive expressions for both parallel and perpendicular components of spin transfer torque (STT) in magnetic tunnel junctions (MTJs), which have several important advantages over the currently available expressions: First they are derived in a more realistic approximation, resulting in excellent agreement with exact results even in the presence of resonant tunneling. Second, we show that they can be expressed in terms of the scattering matrix elements, which gives them a clear physical interpretation. Third, they are given entirely in terms of collinear quantities, which are readily available in existing transport codes. We use these expressions to investigate STT behavior in MTJs with asymmetric barriers at finite bias. The results show that lowering the barrier height in the bulk does not qualitatively change the behavior of STT. The absolute STT increases on account of the overall increase of the barrier transparency; however, the STT efficiency remains in the same range. At the same time, modifications of the interfaces can qualitatively change STT behavior. Thus, interface engineering can be used to control the bias dependence of STT and optimize the performance of STT-based devices. © 2013 American Physical Society.


Mejdoubi A.,CNRS Spintronics and Technology of Components | Prenat G.,CNRS Spintronics and Technology of Components | Dieny B.,CNRS Spintronics and Technology of Components
2012 28th International Conference on Microelectronics - Proceedings, MIEL 2012 | Year: 2012

Magnetic Tunnel Junction (MTJ) devices are CMOS compatible with high stability, high reliability and non-volatility. A macro-model of MTJ with precessional switching is presented in this paper. This model is based on Spin-Transfer Torque (STT) writing approach. The current-induced magnetic switching and excitations was studied in structures comprising a perpendicularly magnetized polarizing layer (PL), an in-plane magnetized free layer (FL), and an in-plane magnetized analyzing layer (AL). © 2012 IEEE.

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