Showing 1–10 of 10 results for author: Laczkowski, P

Spin dependent transport characterization in metallic lateral spin valves using 1D and 3D modeling

Authors: P. Laczkowski, M. Cosset-Cheneau, W. Savero-Torres, V. T. Pham, H. Jaffrès, N. Reyren, J. -C. Rojas-Sànchez, A. Marty, L. Vila, J. -M. George, J. -P. Attané

Abstract: We present the analysis of the spin signals obtained in NiFe based metallic lateral spin valves. We exploit the spin dependent diffusive equations in both the conventional 1D analytic modeling as well as in 3D Finite Element Method simulations. Both approaches are used for extracting the spin diffusion length $l_{sf}^{N}$ and the effective spin polarization $P_{eff}$ in Py/Al, Py/Cu and Py/Au base… ▽ More We present the analysis of the spin signals obtained in NiFe based metallic lateral spin valves. We exploit the spin dependent diffusive equations in both the conventional 1D analytic modeling as well as in 3D Finite Element Method simulations. Both approaches are used for extracting the spin diffusion length $l_{sf}^{N}$ and the effective spin polarization $P_{eff}$ in Py/Al, Py/Cu and Py/Au based lateral nano-structures at both $300\,K$ and $77\,K$. Both the analytic modeling and 3D Finite Element Method simulations give consistent results. Combination of both models provides a powerful tool for reliable spin transport characterization in all metallic spin valves and gives an insight into the spin/charge current and spin accumulations 3D distributions in these devices. We provide the necessary ingredients to develop the 3D finite element modeling of diffusive spin transport. △ Less

Submitted 18 March, 2019; v1 submitted 6 March, 2019; originally announced March 2019.

Comments: 8 pages, 6 figures

Journal ref: Phys. Rev. B 99, 134436 (2019)

Evidence of Pure Spin-Current Generated by Spin Pumping in Interface Localized States in Hybrid Metal-Silicon-Metal Vertical Structures

Authors: C. Cerqueira, J. Y. Qin, H. Dang, A. Djeffal, J. -C. Le Breton, M. Hehn, J. -C. Rojas-Sanchez, X. Devaux, S. Suire, S. Migot, P. Schieffer, J. -G. Mussot, P. Laczkowski, A. Anane, S. Petit-Watelot, M. Stoffel, S. Mangin, Z. Liu, B. W. Cheng, X. F. Han, H. Jaffrès, J. -M. George, Y. Lu

Abstract: Due to the difficulty to grow high quality semiconductors on ferromagnetic metals, the study of spin diffusion transport in Si was only limited to lateral geometry devices. In this work, by using ultra-high vacuum wafer-bonding technique, we have successfully fabricated metal semiconductor metal CoFeB/MgO/Si/Pt vertical structures. We hereby demonstrate pure spin-current injection and transport in… ▽ More Due to the difficulty to grow high quality semiconductors on ferromagnetic metals, the study of spin diffusion transport in Si was only limited to lateral geometry devices. In this work, by using ultra-high vacuum wafer-bonding technique, we have successfully fabricated metal semiconductor metal CoFeB/MgO/Si/Pt vertical structures. We hereby demonstrate pure spin-current injection and transport in the perpendicular current flow geometry over a distance larger than 2μm in n-type Si at room temperature. In those experiments, a pure propagating spin-current is generated via ferromagnetic resonance spin-pumping and converted into a measurable voltage by using the inverse spin-Hall effect occurring in the top Pt layer. A systematic study by varying both Si and MgO thicknesses reveals the important role played by the localized states at the MgO/Si interface for the spin-current generation. Proximity effects involving indirect exchange interactions between the ferromagnet and the MgO/Si interface states appears to be a prerequisite to establish the necessary out-of-equilibrium spin-population in Si under the spin-pumping action. △ Less

Submitted 10 February, 2019; originally announced February 2019.

Journal ref: NanoLett. 19, 90(2019)

Spin diffusion length and polarization of ferromagnetic metals measured by spin-absorption technique in lateral spin valves

Authors: G. Zahnd, Laurent Vila, V. Pham, M Cosset-Cheneau, W Lim, A Brenac, P Laczkowski, A Marty, J Attané

Abstract: We present measurements of pure spin current absorption on lateral spin valves. By varying the width of the absorber we demonstrate that spin current absorption measurements enable to characterize efficiently the spin transport properties of ferromagnetic elements. The analytical model used to describe the measurement takes into account the polarization of the absorber. The analysis of the measure… ▽ More We present measurements of pure spin current absorption on lateral spin valves. By varying the width of the absorber we demonstrate that spin current absorption measurements enable to characterize efficiently the spin transport properties of ferromagnetic elements. The analytical model used to describe the measurement takes into account the polarization of the absorber. The analysis of the measurements allows thus determining the polarization and the spin diffusion length of a studied material independently, contrarily to most experiments based on lateral spin valves where those values are entangled. We report the spin transport parameters of some of the most important materials used in spinorbitronics (Co60Fe40, Ni81Fe19, Co, Pt, and Ta), at room and low (10 K) temperatures. △ Less

Submitted 31 October, 2018; originally announced October 2018.

Comments: Physical Review B, In press

Large enhancement of the spin Hall effect in Au by scattering with side-jump on Ta impurities

Authors: P. Laczkowski, Y. Fu, H. Yang, J. -C. Rojas-Sánchez, P. Noel, V. T. Pham, G. Zahnd, C. Deranlot, S. Collin, C. Bouard, P. Warin, V. Maurel, M. Chshiev, A. Marty, J. -P. Attané, A. Fert, H. Jaffrès, L. Vila, J. -M. George

Abstract: We present measurements of the Spin Hall Effect (SHE) in AuW and AuTa alloys for a large range of W or Ta concentrations by combining experiments on lateral spin valves and Ferromagnetic-Resonance/spin pumping technique. The main result is the identification of a large enhancement of the Spin Hall Angle (SHA) by the side-jump mechanism on Ta impurities, with a SHA as high as + 0.5 (i.e $50\%$) for… ▽ More We present measurements of the Spin Hall Effect (SHE) in AuW and AuTa alloys for a large range of W or Ta concentrations by combining experiments on lateral spin valves and Ferromagnetic-Resonance/spin pumping technique. The main result is the identification of a large enhancement of the Spin Hall Angle (SHA) by the side-jump mechanism on Ta impurities, with a SHA as high as + 0.5 (i.e $50\%$) for about 10\% of Ta. In contrast the SHA in AuW does not exceed + 0.15 and can be explained by intrinsic SHE of the alloy without significant extrinsic contribution from skew or side-jump scattering by W impurities. The AuTa alloys, as they combine a very large SHA with a moderate resistivity (smaller than $85\,μΩ.cm$), are promising for spintronic devices exploiting the SHE. △ Less

Submitted 30 August, 2017; originally announced August 2017.

Comments: 6 pages, 4 figures

Journal ref: Phys. Rev. B 96, 140405 (2017)

Perpendicular magnetization reversal in Pt/[Co/Ni]$_3$/Al multilayers via the Spin Hall Effect of Pt

Authors: J. -C. Rojas-Sánchez, P. Laczkowski, J. Sampaio, S. Collin, K. Bouzehouane, N. Reyren, H. Jaffrès, A. Mougin, J. -M. George

Abstract: We experimentally investigate the current-induced magnetization reversal in Pt/[Co/Ni]$_3$/Al multilayers combining the anomalous Hall effect and magneto-optical Kerr effect techniques in crossbar geometry. The magnetization reversal occurs through nucleation and propagation of a domain of opposite polarity for a current density of the order of 0.3 TA/m$^2$. In these experiments we demonstrate a f… ▽ More We experimentally investigate the current-induced magnetization reversal in Pt/[Co/Ni]$_3$/Al multilayers combining the anomalous Hall effect and magneto-optical Kerr effect techniques in crossbar geometry. The magnetization reversal occurs through nucleation and propagation of a domain of opposite polarity for a current density of the order of 0.3 TA/m$^2$. In these experiments we demonstrate a full control of each stage: i)the Ørsted field controls the domain nucleation and ii) domain-wall propagation occurs by spin torque from the Pt spin Hall effect. This scenario requires an in-plane magnetic field to tune the domain wall center orientation along the current for efficient domain wall propagation. Indeed, as nucleated, domain walls are chiral and Néel like due to the interfacial Dzyaloshinskii-Moriya interaction. △ Less

Submitted 23 November, 2015; originally announced November 2015.

Comments: 5 pages, 3 figures

Journal ref: Appl. Phys. Lett 108, 082406 (2016)

Evaluation of the spin diffusion length of AuW alloy by spin absorption experiments in the limit of large spin-orbit interactions

Authors: P. Laczkowski, H. Jaffrès, W. Savero-Torres, J. -C. Rojas-Sánchez, Y. Fu, N. Reyren, C. Deranlot, L. Notin, C. Beigné, J. -P. Attané, L. Vila, J. -M. George, A. Marty

Abstract: The knowledge of the spin diffusion length $λ_{A}$ is a prerequisite for the estimation of the spin Hall angle. We investigate spin current absorption of materials with small $λ_{A}$ using AuW stripes inserted in lateral spin-valves. Width variations of the AuW stripe lead to drastic changes of the spin absorption, which cannot be explained by conventional analysis. We show that the spin-current p… ▽ More The knowledge of the spin diffusion length $λ_{A}$ is a prerequisite for the estimation of the spin Hall angle. We investigate spin current absorption of materials with small $λ_{A}$ using AuW stripes inserted in lateral spin-valves. Width variations of the AuW stripe lead to drastic changes of the spin absorption, which cannot be explained by conventional analysis. We show that the spin-current polarization and the spin accumulation attenuation in the vicinity of the spin absorber must to be precisely taken into account for accurate estimation of $λ_{A}$. We propose an analytical model supported by numerical calculations that allows to extract proper $λ_{A}$ values of spin Hall effect materials. △ Less

Submitted 27 October, 2015; v1 submitted 16 July, 2015; originally announced July 2015.

Comparison of the use of NiFe and CoFe as electrodes for metallic lateral spin-valves

Authors: G. Zahnd, L. Vila, T. V. Pham, A. Marty, P. Laczkowski, W. Savero Torres, C. Beigné, C. Vergnaud, M. Jamet, J. -P. Attané

Abstract: Spin injection and detection in Co60Fe40-based all-metallic lateral spin-valves have been studied at both room and low temperatures. The obtained spin signals amplitudes have been compared to that of identical Ni80Fe20-based devices. The replacement of Ni80Fe20 by CoFe allows increasing the spin signal amplitude by up to one order of magnitude, thus reaching 50 mΩ at room temperature. The spin sig… ▽ More Spin injection and detection in Co60Fe40-based all-metallic lateral spin-valves have been studied at both room and low temperatures. The obtained spin signals amplitudes have been compared to that of identical Ni80Fe20-based devices. The replacement of Ni80Fe20 by CoFe allows increasing the spin signal amplitude by up to one order of magnitude, thus reaching 50 mΩ at room temperature. The spin signal dependence with the distance between the ferromagnetic electrodes has been analyzed using both a 1D spin transport model and finite elements method simulations. The enhancement of the spin signal amplitude when using CoFe electrodes can be explained by a higher effective polarization. △ Less

Submitted 12 November, 2015; v1 submitted 3 July, 2015; originally announced July 2015.

Comments: 8 pages and 4 figures

Calculation method of spin accumulations and spin signals in nanostructures using spin resistors

Authors: W. Savero Torres, A. Marty, P. Laczkowski, L. Vila, M. Jamet, J-P. Attané

Abstract: The understanding and calculation of spin transport are essential elements for the development of spintronics devices. Here, we propose a simple method to calculate analytically the spin accumulations, spin currents and magnetoresistances in complex systems. This can be used both for CPP experiments in multilayers and for multiterminal nanostructures made of semiconductors, oxides, metals and carb… ▽ More The understanding and calculation of spin transport are essential elements for the development of spintronics devices. Here, we propose a simple method to calculate analytically the spin accumulations, spin currents and magnetoresistances in complex systems. This can be used both for CPP experiments in multilayers and for multiterminal nanostructures made of semiconductors, oxides, metals and carbon allotropes. △ Less

Submitted 8 June, 2015; v1 submitted 3 June, 2015; originally announced June 2015.

Comments: 12 pages and 7 figures

Experimental evidences of a large extrinsic spin Hall effect in AuW alloy

Authors: P. Laczkowski, J. -C. Rojas-Sánchez, W. Savero-Torres, H. Jaffrès, N. Reyren, C. Deranlot, L. Notin, C. Beigné, A. Marty, J. -P. Attané, L. Vila, J. -M. George, A. Fert

Abstract: We report an experimental study of a gold-tungsten alloy (7% at. W concentration in Au host) displaying remarkable properties for spintronics applications using both magneto-transport in lateral spin valve devices and spin-pumping with inverse spin Hall effect experiments. A very large spin Hall angle of about 10% is consistently found using both techniques with the reliable spin diffusion length… ▽ More We report an experimental study of a gold-tungsten alloy (7% at. W concentration in Au host) displaying remarkable properties for spintronics applications using both magneto-transport in lateral spin valve devices and spin-pumping with inverse spin Hall effect experiments. A very large spin Hall angle of about 10% is consistently found using both techniques with the reliable spin diffusion length of 2 nm estimated by the spin sink experiments in the lateral spin valves. With its chemical stability, high resistivity and small induced damping, this AuW alloy may find applications in the nearest future. △ Less

Submitted 22 August, 2014; v1 submitted 27 March, 2014; originally announced March 2014.

Journal ref: Applied Physics Letters 104, 142403 (2014)

Spin Pumping and Inverse Spin Hall Effect in Platinum: The Essential Role of Spin-Memory Loss at Metallic Interfaces

Authors: J. -C. Rojas-Sánchez, N. Reyren, P. Laczkowski, W. Savero, J. -P. Attané, C. Deranlot, M. Jamet, J. -M. George, L. Vila, H. Jaffrès

Abstract: Through combined ferromagnetic resonance, spin-pumping and inverse spin Hall effect experiments in Co|Pt bilayers and Co|Cu|Pt trilayers, we demonstrate consistent values of spin diffusion length $\ell_{\rm sf}^{\rm Pt}=3.4\pm0.4$ nm and of spin Hall angle $θ_{\rm SHE}^{\rm Pt}=0.051\pm0.004$ for Pt. Our data and model emphasize on the partial depolarization of the spin current at each interface d… ▽ More Through combined ferromagnetic resonance, spin-pumping and inverse spin Hall effect experiments in Co|Pt bilayers and Co|Cu|Pt trilayers, we demonstrate consistent values of spin diffusion length $\ell_{\rm sf}^{\rm Pt}=3.4\pm0.4$ nm and of spin Hall angle $θ_{\rm SHE}^{\rm Pt}=0.051\pm0.004$ for Pt. Our data and model emphasize on the partial depolarization of the spin current at each interface due to spin-memory loss. Our model reconciles the previously published spin Hall angle values and explains the different scaling lengths for the ferromagnetic damping and the spin Hall effect induced voltage. △ Less

Submitted 17 March, 2014; v1 submitted 10 December, 2013; originally announced December 2013.

Comments: 6 pages, 3 figures (main text) and 8 pages supplementary. Published with small modifications in Phys. Rev. Lett

Journal ref: Physical Review Letters 112, 106602 (2014)