Large enhancement of bulk spin polarization by suppressing CoMn anti-sites in Co2Mn(Ge0.75Ga0.25) Heusler alloy thin film

S. Li; Y. K. Takahashi; Y. Sakuraba; N. Tsuji; H. Tajiri; Y. Miura; J. Chen; T. Furubayashi; K. Hono

doi:10.1063/1.4944719

Large enhancement of bulk spin polarization by suppressing Co_Mn anti-sites in Co₂Mn(Ge_0.75Ga_0.25) Heusler alloy thin film

S. Li, Y. K. Takahashi, Y. Sakuraba^*, N. Tsuji, H. Tajiri, Y. Miura, J. Chen, T. Furubayashi, K. Hono

^*Corresponding author for this work

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

26 Citations (Scopus)

Abstract

We have investigated the structure and magneto-transport properties of Co₂Mn(Ge_0.75Ga_0.25) (CMGG) Heusler alloy thin films with near-stoichiometric and Mn-rich compositions in order to understand the effect of Co-Mn anti-sites on bulk spin polarization. Anomalous x-ray diffraction measurements using synchrotron radiated x-rays confirmed that Co_Mn anti-sites easily form in the near-stoichiometric CMGG compound at annealing temperature higher than 400 °C, while it can be suppressed in Mn-rich CMGG films. Accordingly, large enhancement in negative anisotropic magnetoresistance of CMGG films and giant magnetoresistance (GMR) in current-perpendicular-to-plane (CPP) pseudo spin valves were observed in the Mn-rich composition. A large resistance-area product change (ΔRA) of 12.8 mΩ μm² was demonstrated in the CPP-GMR pseudo spin valves using the Mn-rich CMGG layers after annealing at 600 °C. It is almost twice of the maximum output observed in the CPP-GMR pseudo spin valves using the near-stoichiometric CMGG. These indicate that the spin polarization of CMGG is enhanced in the Mn-rich composition through suppressing the formation of Co_Mn-antisites in CMGG films, being consistent with first-principle calculation results.

Original language	English
Article number	122404
Journal	Applied Physics Letters
Volume	108
Issue number	12
DOIs	https://doi.org/10.1063/1.4944719
Publication status	Published - 2016 Mar 21
Externally published	Yes

ASJC Scopus subject areas

Physics and Astronomy (miscellaneous)

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@article{58755423046f4c16aae3aa314ab90b29,

title = "Large enhancement of bulk spin polarization by suppressing CoMn anti-sites in Co2Mn(Ge0.75Ga0.25) Heusler alloy thin film",

abstract = "We have investigated the structure and magneto-transport properties of Co2Mn(Ge0.75Ga0.25) (CMGG) Heusler alloy thin films with near-stoichiometric and Mn-rich compositions in order to understand the effect of Co-Mn anti-sites on bulk spin polarization. Anomalous x-ray diffraction measurements using synchrotron radiated x-rays confirmed that CoMn anti-sites easily form in the near-stoichiometric CMGG compound at annealing temperature higher than 400 °C, while it can be suppressed in Mn-rich CMGG films. Accordingly, large enhancement in negative anisotropic magnetoresistance of CMGG films and giant magnetoresistance (GMR) in current-perpendicular-to-plane (CPP) pseudo spin valves were observed in the Mn-rich composition. A large resistance-area product change (ΔRA) of 12.8 mΩ μm2 was demonstrated in the CPP-GMR pseudo spin valves using the Mn-rich CMGG layers after annealing at 600 °C. It is almost twice of the maximum output observed in the CPP-GMR pseudo spin valves using the near-stoichiometric CMGG. These indicate that the spin polarization of CMGG is enhanced in the Mn-rich composition through suppressing the formation of CoMn-antisites in CMGG films, being consistent with first-principle calculation results.",

author = "S. Li and Takahashi, {Y. K.} and Y. Sakuraba and N. Tsuji and H. Tajiri and Y. Miura and J. Chen and T. Furubayashi and K. Hono",

note = "Funding Information: The authors thank Dr. T. Nakamura and T. Koganezawa for their support for the X-ray diffraction experiments in SPring-8. The synchrotron radiation experiment was carried out under the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal Nos. 2015B0903 and 2015B1978). This work was supported in part by the Grant-in-aid for Scientific Research (A) (Grant No. 25249087) from the Japan Society for the Promotion of Science (JSPS), the Advanced Storage Technology Consortium (ASTC) of IDEMA, and the ImPACT Program of Council for Science, Technology and Innovation, Japan. Publisher Copyright: {\textcopyright} 2016 AIP Publishing LLC.",

year = "2016",

month = mar,

day = "21",

doi = "10.1063/1.4944719",

language = "English",

volume = "108",

journal = "Applied Physics Letters",

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TY - JOUR

T1 - Large enhancement of bulk spin polarization by suppressing CoMn anti-sites in Co2Mn(Ge0.75Ga0.25) Heusler alloy thin film

AU - Li, S.

AU - Takahashi, Y. K.

AU - Sakuraba, Y.

AU - Tsuji, N.

AU - Tajiri, H.

AU - Miura, Y.

AU - Chen, J.

AU - Furubayashi, T.

AU - Hono, K.

N1 - Funding Information: The authors thank Dr. T. Nakamura and T. Koganezawa for their support for the X-ray diffraction experiments in SPring-8. The synchrotron radiation experiment was carried out under the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal Nos. 2015B0903 and 2015B1978). This work was supported in part by the Grant-in-aid for Scientific Research (A) (Grant No. 25249087) from the Japan Society for the Promotion of Science (JSPS), the Advanced Storage Technology Consortium (ASTC) of IDEMA, and the ImPACT Program of Council for Science, Technology and Innovation, Japan. Publisher Copyright: © 2016 AIP Publishing LLC.

PY - 2016/3/21

Y1 - 2016/3/21

N2 - We have investigated the structure and magneto-transport properties of Co2Mn(Ge0.75Ga0.25) (CMGG) Heusler alloy thin films with near-stoichiometric and Mn-rich compositions in order to understand the effect of Co-Mn anti-sites on bulk spin polarization. Anomalous x-ray diffraction measurements using synchrotron radiated x-rays confirmed that CoMn anti-sites easily form in the near-stoichiometric CMGG compound at annealing temperature higher than 400 °C, while it can be suppressed in Mn-rich CMGG films. Accordingly, large enhancement in negative anisotropic magnetoresistance of CMGG films and giant magnetoresistance (GMR) in current-perpendicular-to-plane (CPP) pseudo spin valves were observed in the Mn-rich composition. A large resistance-area product change (ΔRA) of 12.8 mΩ μm2 was demonstrated in the CPP-GMR pseudo spin valves using the Mn-rich CMGG layers after annealing at 600 °C. It is almost twice of the maximum output observed in the CPP-GMR pseudo spin valves using the near-stoichiometric CMGG. These indicate that the spin polarization of CMGG is enhanced in the Mn-rich composition through suppressing the formation of CoMn-antisites in CMGG films, being consistent with first-principle calculation results.

AB - We have investigated the structure and magneto-transport properties of Co2Mn(Ge0.75Ga0.25) (CMGG) Heusler alloy thin films with near-stoichiometric and Mn-rich compositions in order to understand the effect of Co-Mn anti-sites on bulk spin polarization. Anomalous x-ray diffraction measurements using synchrotron radiated x-rays confirmed that CoMn anti-sites easily form in the near-stoichiometric CMGG compound at annealing temperature higher than 400 °C, while it can be suppressed in Mn-rich CMGG films. Accordingly, large enhancement in negative anisotropic magnetoresistance of CMGG films and giant magnetoresistance (GMR) in current-perpendicular-to-plane (CPP) pseudo spin valves were observed in the Mn-rich composition. A large resistance-area product change (ΔRA) of 12.8 mΩ μm2 was demonstrated in the CPP-GMR pseudo spin valves using the Mn-rich CMGG layers after annealing at 600 °C. It is almost twice of the maximum output observed in the CPP-GMR pseudo spin valves using the near-stoichiometric CMGG. These indicate that the spin polarization of CMGG is enhanced in the Mn-rich composition through suppressing the formation of CoMn-antisites in CMGG films, being consistent with first-principle calculation results.

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M1 - 122404

ER -

Large enhancement of bulk spin polarization by suppressing Co_Mn anti-sites in Co₂Mn(Ge_0.75Ga_0.25) Heusler alloy thin film

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