Direct imaging of thermally-activated grain-boundary diffusion in Cu/Co/IrMn/Pt exchange-bias structures using atom-probe tomography

Letellier, F.; Lardé, R.; Lechevallier, L.; Akmaldinov, K.; Auffret, S.; Dieny, B.

doi:10.1063/1.4902954

Title: Direct imaging of thermally-activated grain-boundary diffusion in Cu/Co/IrMn/Pt exchange-bias structures using atom-probe tomography

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Abstract

Magnetic devices are often subject to thermal processing steps, such as field cooling to set exchange bias and annealing to crystallize amorphous magnetic electrodes. These processing steps may result in interdiffusion and the subsequent deterioration of magnetic properties. In this study, we investigated thermally-activated diffusion in Cu/Co/IrMn/Pt exchange biased polycrystalline thin-film structures using atom probe tomography. Images taken after annealing at 400 °C for 60 min revealed Mn diffusion into Co grains at the Co/IrMn interface and along Pt grain boundaries for the IrMn/Pt stack, i.e., a Harrison type C regime. Annealing at 500 °C showed further Mn diffusion into Co grains. At the IrMn/Pt interface, annealing at 500 °C led to a type B behavior since Mn diffusion was detected both along Pt grain boundaries and also into Pt grains. The deterioration of the films' exchange bias properties upon annealing was correlated to the observed diffusion. In particular, the topmost Pt capping layer thickness turned out to be crucial since a faster deterioration of the exchange bias properties for thicker caps was observed. This is consistent with the idea that Pt acts as a getter for Mn, drawing Mn out of the IrMn layer.

Authors:

Letellier, F.; Lardé, R.; Lechevallier, L. ^[1]; Akmaldinov, K. ^[2]; Auffret, S.; Dieny, B.

Groupe de Physique des Matériaux, UMR 6634 CNRS/Université et INSA de Rouen, F-76801 Saint Etienne du Rouvray (France)
SPINTEC, Univ. Grenoble-Alpes/CNRS/INAC-CEA, F-38000 Grenoble (France)

Publication Date:: Fri Nov 28 00:00:00 EST 2014

OSTI Identifier:: 22402697

Resource Type:: Journal Article

Journal Name:: Journal of Applied Physics

Additional Journal Information:: Journal Volume: 116; Journal Issue: 20; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-8979

Country of Publication:: United States

Language:: English

Subject:: 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ANNEALING; DIFFUSION; GRAIN BOUNDARIES; INTERFACES; LAYERS; MAGNETIC PROPERTIES; POLYCRYSTALS; THICKNESS; THIN FILMS; TOMOGRAPHY

Citation Formats


                    Letellier, F., Lardé, R., Le Breton, J.-M., E-mail: jean-marie.lebreton@univ-rouen.fr, Lechevallier, L., Département de GEII, Université de Cergy-Pontoise, F-95031 Cergy-Pontoise, Akmaldinov, K., CROCUS Technology, F-38025 Grenoble, Auffret, S., Dieny, B., and Baltz, V., E-mail: vincent.baltz@cea.fr. Direct imaging of thermally-activated grain-boundary diffusion in Cu/Co/IrMn/Pt exchange-bias structures using atom-probe tomography.  United States: N. p., 2014. 
        Web.  doi:10.1063/1.4902954.

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                    Letellier, F., Lardé, R., Le Breton, J.-M., E-mail: jean-marie.lebreton@univ-rouen.fr, Lechevallier, L., Département de GEII, Université de Cergy-Pontoise, F-95031 Cergy-Pontoise, Akmaldinov, K., CROCUS Technology, F-38025 Grenoble, Auffret, S., Dieny, B., & Baltz, V., E-mail: vincent.baltz@cea.fr. Direct imaging of thermally-activated grain-boundary diffusion in Cu/Co/IrMn/Pt exchange-bias structures using atom-probe tomography.  United States.  https://doi.org/10.1063/1.4902954

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                    Letellier, F., Lardé, R., Le Breton, J.-M., E-mail: jean-marie.lebreton@univ-rouen.fr, Lechevallier, L., Département de GEII, Université de Cergy-Pontoise, F-95031 Cergy-Pontoise, Akmaldinov, K., CROCUS Technology, F-38025 Grenoble, Auffret, S., Dieny, B., and Baltz, V., E-mail: vincent.baltz@cea.fr. 2014.  
        "Direct imaging of thermally-activated grain-boundary diffusion in Cu/Co/IrMn/Pt exchange-bias structures using atom-probe tomography".  United States.  https://doi.org/10.1063/1.4902954.

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@article{osti_22402697,

  title        = {Direct imaging of thermally-activated grain-boundary diffusion in Cu/Co/IrMn/Pt exchange-bias structures using atom-probe tomography},

  author       = {Letellier, F. and Lardé, R. and Le Breton, J.-M., E-mail: jean-marie.lebreton@univ-rouen.fr and Lechevallier, L. and Département de GEII, Université de Cergy-Pontoise, F-95031 Cergy-Pontoise and Akmaldinov, K. and CROCUS Technology, F-38025 Grenoble and Auffret, S. and Dieny, B. and Baltz, V., E-mail: vincent.baltz@cea.fr},

  abstractNote = {Magnetic devices are often subject to thermal processing steps, such as field cooling to set exchange bias and annealing to crystallize amorphous magnetic electrodes. These processing steps may result in interdiffusion and the subsequent deterioration of magnetic properties. In this study, we investigated thermally-activated diffusion in Cu/Co/IrMn/Pt exchange biased polycrystalline thin-film structures using atom probe tomography. Images taken after annealing at 400 °C for 60 min revealed Mn diffusion into Co grains at the Co/IrMn interface and along Pt grain boundaries for the IrMn/Pt stack, i.e., a Harrison type C regime. Annealing at 500 °C showed further Mn diffusion into Co grains. At the IrMn/Pt interface, annealing at 500 °C led to a type B behavior since Mn diffusion was detected both along Pt grain boundaries and also into Pt grains. The deterioration of the films' exchange bias properties upon annealing was correlated to the observed diffusion. In particular, the topmost Pt capping layer thickness turned out to be crucial since a faster deterioration of the exchange bias properties for thicker caps was observed. This is consistent with the idea that Pt acts as a getter for Mn, drawing Mn out of the IrMn layer.},

  doi          = {10.1063/1.4902954},

  url          = {https://www.osti.gov/biblio/22402697},
  journal      = {Journal of Applied Physics},

  issn         = {0021-8979},

  number       = 20,

  volume       = 116,

  place        = {United States},

  year         = {Fri Nov 28 00:00:00 EST 2014},

  month        = {Fri Nov 28 00:00:00 EST 2014}

}

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