Characterization of iron ferromagnetism by the local atomic volume: from three-dimensional structures to isolated atoms

ZHANG, Lei, Mojmír ŠOB, Zhe WU, Ying ZHANG and Guang-Hong LU. Characterization of iron ferromagnetism by the local atomic volume: from three-dimensional structures to isolated atoms. J. Phys. Condens. Matter. Bristol: IOP Publishing Ltd, 2014, vol. 26, No 8, p. "nestránkováno", 17 pp. ISSN 0953-8984. Available from: https://dx.doi.org/10.1088/0953-8984/26/8/086002.

Basic information

• Original name: Characterization of iron ferromagnetism by the local atomic volume: from three-dimensional structures to isolated atoms
• Authors: ZHANG, Lei (156 China), Mojmír ŠOB (203 Czech Republic, guarantor, belonging to the institution), Zhe WU (156 China), Ying ZHANG (156 China) and Guang-Hong LU (156 China).
• Edition: J. Phys. Condens. Matter, Bristol, IOP Publishing Ltd, 2014, 0953-8984.

Other information

• Original language: English
• Type of outcome: Article in a journal
• Field of Study: 10302 Condensed matter physics
• Country of publisher: United Kingdom of Great Britain and Northern Ireland
• Confidentiality degree: is not subject to a state or trade secret
• WWW: URL
• Impact factor: Impact factor: 2.346
• RIV identification code: RIV/00216224:14740/14:00077376
• Organization unit: Central European Institute of Technology
• Doi: http://dx.doi.org/10.1088/0953-8984/26/8/086002
• UT WoS: 000331952100010
• Keywords in English: 3D TRANSITION-METALS; AB-INITIO; MAGNETIC-MOMENT; MONATOMIC WIRE; FCC IRON; CLUSTERS; BCC; PSEUDOPOTENTIALS; BEHAVIOR; FE
• Tags: kontrola MP, MP, rivok
• Tags: International impact, Reviewed

Abstract

We present a comprehensive study of the relationship between the ferromagnetism and the structural properties of Fe systems from three-dimensional ones to isolated atoms based on the spin-density functional theory. We have found a relation between the magnetic moment and the volume of the Voronoi polyhedron, determining, in most cases, the value of the total magnetic moment as a function of this volume with an average accuracy of +/-0.28 mu(B) and of the 3d magnetic moment with an average accuracy of +/-0.07 mu(B) when the atomic volume is larger than 22 angstrom(3). It is demonstrated that this approach is applicable for many three-dimensional systems, including high-symmetry structures of perfect body-centered cubic (bcc), face-centered cubic (fcc), hexagonal close-packed (hcp), double hexagonal close-packed (dhcp), and simple cubic (sc) crystals, as well as for lower-symmetry ones, for example atoms near a grain boundary (GB) or a surface, around a vacancy or in a linear chain (for low-dimensional cases, we provide a generalized definition of the Voronoi polyhedron). Also, we extend the validity of the Stoner model to low-dimensional structures, such as atomic chains, free-standing monolayers and surfaces, determining the Stoner parameter for these systems. The ratio of the 3d-exchange splitting to the magnetic moment, corresponding to the Stoner parameter, is found to be I-3d = (0.998 +/- 0.006) eV/mu(B) for magnetic moments up to 3.0 mu(B). Further, the 3d exchange splitting changes nearly linearly in the region of higher magnetic moments (3.0-4.0 mu(B)) and the corresponding Stoner exchange parameter equals I-3d(h) = (0.272 +/- 0.006) eV/mu(B). The existence of these two regions reflects the fact that, with increasing Voronoi volume, the 3d bands separate first and, consequently, the 3d magnetic moment increases. When the Voronoi volume is sufficiently large (>= 22 angstrom(3)), the separation of the 3d bands is complete and the magnetic moment reaches a value of 3.0 mu(B). Then, when the volume further increases, the 4s bands start to separate, increasing thus the 4s magnetic moment. Surprisingly, in the region of higher magnetic moments (>= 3.0 mu(B)), there is also a linear relationship between the 4s exchange splitting and the total magnetic moment with a slope of I-4s(h) = (1.053 +/- 0.016) eV/mu(B), which is nearly identical to I-3d for magnetic moments up to 3.0 mu(B). These linear relations can be considered as an extension of the Stoner model for low-dimensional systems.

Links

• ED1.1.00/02.0068, research and development project: Name: CEITEC - central european institute of technology