### Abstract

On the basis of the torque correlation model for the Gilbert damping constant α, we perform the first principles calculation for α for Co-based Heusler alloys, Co2MnAl (CMA), Co2MnSi (CMS), and Co2FeSi (CFS). In the ordered (L21) and partially disordered (B2) structures, the calculated values of α reflect half-metallicity or the gap structure around the Fermi level, EF, i.e. CMS with 100% spin-polarization has the smallest value. The valence electron number dependence of α follows the experimental trend. However, the calculated values are almost a factor of ten smaller than the measured ones. Although the α values are larger in the completely disordered (A2) structure, they are not as large as the experimental results. Therefore, the decreasing degree of order or the breakdown of the half-metallicity is not responsible for the discrepancy.

Original language | English |
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Article number | 164011 |

Journal | Journal of Physics D: Applied Physics |

Volume | 48 |

Issue number | 16 |

DOIs | |

Publication status | Published - 2015 Apr 29 |

### Keywords

- CPA
- Co<inf>2</inf>FeSi
- Co<inf>2</inf>MnAl
- Co<inf>2</inf>MnSi
- Gilbert damping constant
- Heusler alloys
- TB-LMTO
- first-principles calculations
- half-metals
- spin relaxation
- spintronics

### ASJC Scopus subject areas

- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Acoustics and Ultrasonics
- Surfaces, Coatings and Films