Co72Fe20B8 : structure, magnetism, and tunneling spin polarization

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We present measurements of tunneling spin polarization of Co72Fe20B8 in Al/AlOx/CoFeB tunnel junctions using superconducting tunneling spectroscopy. We consistently observe high spin polarization (above 53%), higher than that measured for comparable CoFe alloys, indicating a crucial role played by the 8% atomic boron. X-ray diffraction measurements on 700 Å thick films reveal an amorphous structure for as-deposited films, while anneals above 250¿°C initiate a gradual crystallization. Superconducting quantum interference device magnetometery shows that the magnetic moment exhibits minor changes after anneals, but there is a dramatic change in the coercivity after anneals above 400¿°C. However, these structural and magnetic changes induce only a slight change in the tunneling spin polarization of CoFeB.
Original languageEnglish
Title of host publicationProceedings of the 50th Annual Conference on Magnetism & Magnetic Materials, 30 October - 3 November 2005, San José, California, USA
Publication statusPublished - 2005

Publication series

NameJournal of Applied Physics
ISSN (Print)0021-8979


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