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Free keywords:
Binary alloys, Curie temperature, Density functional theory, Ferromagnetic materials, Ferromagnetism, Gold, Gold alloys, Magnetic moments, Magnetocrystalline anisotropy, Ferromagnetic exchange, Ferromagnets, High Curie temperature, Localised, Localized magnetic moments, Metallics, Nearest-neighbour, Orbital moment, Spin moments, Spin-orbit couplings, Manganese alloys
Abstract:
Metallic Mn-based alloys with a nearest-neighbor Mn-Mn distance greater than 0.4 nm exhibit large, well-localized magnetic moments. Here we investigate the magnetism of tetragonal Au4Mn with a Curie temperature of 385 K, where manganese has a spin moment of 4.1μB and its orbital moment is quenched. Since 80% of the atoms are gold, the spin-orbit interaction is strong and Au4Mn exhibits uniaxial magnetocrystalline anisotropy with surface maze domains at room temperature. The magnetic hardness parameter of 1.0 is sufficient to maintain the magnetization along the c axis for a sample of any shape. Au also reduces the spin moment of Mn through 5d-3d orbital hybridization. An induced moment of 0.05μB was found on Au under a pulsed field of 40 T. Density functional theory calculations indicate that the Mn-Mn exchange is mediated by spin-polarized gold 5d and 6p electrons. The distance dependence shows that it is ferromagnetic or zero for the first ten shells of Mn neighbors out to 1.041 nm (64 atoms), and very weak and oscillatory thereafter. © 2022 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Open access publication funded by the Max Planck Society.
