### Abstract

Heusler alloys have been known since the 19^{th} century and have fascinated researchers because of their wide range of applications, especially related to their magnetic properties. The magnetic moment of a few of these materials can be predicted by simply counting their valance electrons [this is called the Slater-Pauling (SP) rule]. However, this simple counting rule does not work in many other cases. Inverse-Heusler alloys are a sub-class of Heusler alloys, and in many cases also do not follow the SP rule. Fe_{2}CuAl (FCA) is an inverse-Heusler alloy for which the SP rule predicts a magnetic moment of 2.00 μB. However, experimental results give a magnetic moment of 3.30 μB. Motivated by this discrepancy, we study this material theoretically to gain a microscopic understanding of how the magnetic moment forms. For this purpose, we construct a first-principles-based tight-binding model incorporating an on-site Hubbard repulsion U between each d orbital and a Hund coupling J between different d orbitals of a given atom in the system. We use the Green's function technique and apply the mean-field approximation to solve the model. The results show the magnetic moment of FCA depends on U and J. We find that the magnetic moment given by the SP rule (2.00 μB) corresponds to a plateau in our magnetic moment vs J curves for various values of U, and that the experimental magnetic moment (3.30 μB) corresponds to a point on the curves rising above the plateau.

Original language | English |
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Article number | 012009 |

Journal | Journal of Physics: Conference Series |

Volume | 1442 |

Issue number | 1 |

DOIs | |

Publication status | Published - 29 Jan 2020 |

Event | Basic and Applied Sciences Interdisciplinary Conference 2017, BASIC 2017 - , Indonesia Duration: 18 Aug 2017 → 19 Aug 2017 |

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_{2}CuAl via first-principles-based tight-binding model.

*Journal of Physics: Conference Series*,

*1442*(1), [012009]. https://doi.org/10.1088/1742-6596/1442/1/012009