Boron segregation in crystallized MgO/amorphous- Co40 Fe40 B20 thin films

C. Y. You; T. Ohkubo; Y. K. Takahashi; K. Hono

doi:10.1063/1.2963709

Boron segregation in crystallized MgO/amorphous- Co40 Fe40 B20 thin films

C. Y. You, T. Ohkubo, Y. K. Takahashi, K. Hono

Research output: Contribution to journal › Article › peer-review

42 Citations (Scopus)

Abstract

We have investigated the crystallization process of an amorphous Co40 Fe40 B20 ribbon and a MgO/ amorphous-Co40 Fe40 B20 thin film to simulate the segregation of B in the magnetic tunneling junctions that use CoFeB ferromagnetic electrodes and a MgO tunneling barrier. Both types of samples show the same crystallization sequence: a primary crystallization of bcc-FeCo from an amorphous precursor followed by boride crystallization at a higher annealing temperature. Three-dimensional atom probe analysis has shown that very little boron is dissolved in the bcc-FeCo crystals (∼1 at. %). A transmission electron microscopy observation of an annealed MgO/ Co40 Fe40 B20 bilayer thin film has shown clear evidence of MgO serving as heterogeneous nucleation sites for bcc-FeCo grains. Energy filtering transmission electron microscopy has shown strong boron segregation at the MgO/FeCo interface after the crystallization of the MgO/ amorphous-Co40 Fe40 B20 bilayer film.

Original language	English
Article number	033517
Journal	Journal of Applied Physics
Volume	104
Issue number	3
DOIs	https://doi.org/10.1063/1.2963709
Publication status	Published - 2008
Externally published	Yes

ASJC Scopus subject areas

Physics and Astronomy(all)

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title = "Boron segregation in crystallized MgO/amorphous- Co40 Fe40 B20 thin films",

abstract = "We have investigated the crystallization process of an amorphous Co40 Fe40 B20 ribbon and a MgO/ amorphous-Co40 Fe40 B20 thin film to simulate the segregation of B in the magnetic tunneling junctions that use CoFeB ferromagnetic electrodes and a MgO tunneling barrier. Both types of samples show the same crystallization sequence: a primary crystallization of bcc-FeCo from an amorphous precursor followed by boride crystallization at a higher annealing temperature. Three-dimensional atom probe analysis has shown that very little boron is dissolved in the bcc-FeCo crystals (∼1 at. %). A transmission electron microscopy observation of an annealed MgO/ Co40 Fe40 B20 bilayer thin film has shown clear evidence of MgO serving as heterogeneous nucleation sites for bcc-FeCo grains. Energy filtering transmission electron microscopy has shown strong boron segregation at the MgO/FeCo interface after the crystallization of the MgO/ amorphous-Co40 Fe40 B20 bilayer film.",

author = "You, {C. Y.} and T. Ohkubo and Takahashi, {Y. K.} and K. Hono",

note = "Funding Information: This work was in part supported by CREST, JST, the Grant-in-Aid for Scientific Research on Priority Area on “Spin Current,” and the World Premier International Research Center Initiative (WPI Initiative) on Materials Nanoarchitronics, MEXT, Japan.",

year = "2008",

doi = "10.1063/1.2963709",

language = "English",

volume = "104",

journal = "Journal of Applied Physics",

issn = "0021-8979",

publisher = "American Institute of Physics Publising LLC",

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T1 - Boron segregation in crystallized MgO/amorphous- Co40 Fe40 B20 thin films

AU - You, C. Y.

AU - Ohkubo, T.

AU - Takahashi, Y. K.

AU - Hono, K.

N1 - Funding Information: This work was in part supported by CREST, JST, the Grant-in-Aid for Scientific Research on Priority Area on “Spin Current,” and the World Premier International Research Center Initiative (WPI Initiative) on Materials Nanoarchitronics, MEXT, Japan.

PY - 2008

Y1 - 2008

N2 - We have investigated the crystallization process of an amorphous Co40 Fe40 B20 ribbon and a MgO/ amorphous-Co40 Fe40 B20 thin film to simulate the segregation of B in the magnetic tunneling junctions that use CoFeB ferromagnetic electrodes and a MgO tunneling barrier. Both types of samples show the same crystallization sequence: a primary crystallization of bcc-FeCo from an amorphous precursor followed by boride crystallization at a higher annealing temperature. Three-dimensional atom probe analysis has shown that very little boron is dissolved in the bcc-FeCo crystals (∼1 at. %). A transmission electron microscopy observation of an annealed MgO/ Co40 Fe40 B20 bilayer thin film has shown clear evidence of MgO serving as heterogeneous nucleation sites for bcc-FeCo grains. Energy filtering transmission electron microscopy has shown strong boron segregation at the MgO/FeCo interface after the crystallization of the MgO/ amorphous-Co40 Fe40 B20 bilayer film.

AB - We have investigated the crystallization process of an amorphous Co40 Fe40 B20 ribbon and a MgO/ amorphous-Co40 Fe40 B20 thin film to simulate the segregation of B in the magnetic tunneling junctions that use CoFeB ferromagnetic electrodes and a MgO tunneling barrier. Both types of samples show the same crystallization sequence: a primary crystallization of bcc-FeCo from an amorphous precursor followed by boride crystallization at a higher annealing temperature. Three-dimensional atom probe analysis has shown that very little boron is dissolved in the bcc-FeCo crystals (∼1 at. %). A transmission electron microscopy observation of an annealed MgO/ Co40 Fe40 B20 bilayer thin film has shown clear evidence of MgO serving as heterogeneous nucleation sites for bcc-FeCo grains. Energy filtering transmission electron microscopy has shown strong boron segregation at the MgO/FeCo interface after the crystallization of the MgO/ amorphous-Co40 Fe40 B20 bilayer film.

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JF - Journal of Applied Physics

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M1 - 033517

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Boron segregation in crystallized MgO/amorphous- Co40 Fe40 B20 thin films

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