<i>Ab initio</i>study of Co and Ni under uniaxial and biaxial loading and in epitaxial overlayers

Zelený, Michal; Legut, Dominik; Šob, Mojmı́r

doi:10.1103/physrevb.78.224105

Cited by 27 publications

(15 citation statements)

References 71 publications

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“…Perdew, Burke, and Ernzerhof (PBE) 43 is used to evaluate the exchange-correlation energy because the GGA functional can accurately reproduce the structural and magnetic ground state of bcc iron. 4,5,27,44 A full vector-field description of the magnetization density that allows continuous variation in the direction of the local magnetic moments between atoms is required to accurately identify the noncollinear SS state. To this end, we perform fully unconstrained noncollinear magnetic calculations within the PAW formalism, as implemented in the VASP code by Hobbs et al 45 In addition, we apply the generalized Bloch equations to analyze the incommensurate SS state.…”

Section: A Simulation Methodsmentioning

confidence: 99%

“…On the other hand, epitaxial strain introduced by a lattice mismatch between a film and a substrate often plays an important role in determining the magnetic ground state; for example, a FM-to-antiferromagnetic (AFM) phase transition has been observed in Fe(001) thin films. 4,[27][28][29][30][31][32] Hence, the emergence of a noncollinear SS structure in the monolayer should be discussed by considering the effect of epitaxial in-plane strain.…”

Section: Introductionmentioning

confidence: 99%

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Ab initiostudy of spin-spiral noncollinear magnetism in a free-standing Fe(110) monolayer under in-plane strain

2012

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We investigate the magnetic phase transition from collinear ferromagnetic (FM) ordering to noncollinear spin-spiral (SS) ordering in an Fe(110) monolayer under in-plane strain by performing fully unconstrained first-principles spin-density-functional calculations. The FM Fe(110) monolayer undergoes a FM-SS phase transition on the application of in-plane compression, whereas the application of tension keeps the system FM. The stability and wavelength of the excited SS state are further increased by compressive strains, especially along [110]. The FM-SS transition in the isotropically strained monolayer is dominated by competing exchange interactions between the ferromagnetically coupled first neighbor and the antiferromagnetically coupled second neighbor; the third neighbor also contributes to the transition under anisotropic strain. In addition, we demonstrate the stabilization mechanism of SS noncollinear magnetism from the electronic band structures: The noncollinear SS state is stabilized by a remarkable interband repulsion between the majority and minority spins, which occurs under in-plane compression.

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Section: A Simulation Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ab initiostudy of spin-spiral noncollinear magnetism in a free-standing Fe(110) monolayer under in-plane strain

2012

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“…32 To evaluate the exchange-correlation energy, we employed the GGA of the Perdew-Burke-Ernzerhof ͑PBE͒ functional, 21 which successfully yielded the structural and magnetic ground state of iron. 17,33 Within the GGA, the preliminarily calculated lattice constant a 0 = 2.831 Å, magnetic moment M = 2.20 B , and elastic constants C 11 = 247 GPa, C 12 = 143 GPa, and C 44 = 105 GPa for the FM bcc iron bulk were in good agreement with the experimental values 34,35 of a 0 = 2.867 Å, M = 2.22 B , and C 11 = 243 GPa, C 12 = 139 GPa. and C 44 = 122 GPa, respectively.…”

Section: A Simulation Methodsmentioning

confidence: 99%

“…The resulting in-plane strain induces tetragonal distortions to the lattice of film, which lead to a crystalline structure transformation from bcc ͑␣͒ to fcc ͑␥͒. The deformation from bcc to fcc is known as the ͑epitaxial͒ Bain's transformation path 13 and has been used to theoretically investigate the magnetic phase diagram of transition-metal thin films grown on various substrates: [14][15][16][17][18][19] Friák et al 14 investigated the magnetic phase boundaries in iron along the Bain's path with various volumes using ab initio full-potential linearized augmented plane-wave ͑FLAPW͒ method, which included the collinear magnetic orderings of the FM, nonmagnetic ͑NM͒, single-layer-antiferromagnetic ͑AFM1-↑↓ ↑ ↓...͒ and double-layer-antiferromagnetic ͑AFMD-↑↑ ↓ ↓...͒ 9 states. They showed that theoretically predicted FM/AFMD/AFM1 phase boundaries agreed well with the experimental observations within the generalized gradient approximation ͑GGA͒.…”

Section: Introductionmentioning

confidence: 99%

Ab initiostudy of magnetism at iron surfaces under epitaxial in-plane strain

2010

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We investigated magnetism at the ͑001͒ surface of iron and its response to the epitaxial in-plane strain that corresponds to bcc-fcc ͑Bain's͒ transformation path using ab initio ͑first-principles͒ spin-density-functional theory calculations within the generalized gradient approximation. The magnetic moment is enhanced at the surface of a ferromagnetic ͑FM͒ film under a strain-free condition. This was caused by electron rearrangement from the minority-t 2g to majority-t 2g state due to the decrease in nearest neighbors at the surface. Under in-plane strain, the magnetic and structural phase transition from the FM-bcc to double-layerantiferromagnetic-fcc occurred at the critical strain of = −0.09, accompanying directional bond switching from the nearest-to second-nearest neighbors in the minority spin. The transition caused a discontinuous change in the magnetic moments on the inner layers of the film across the transition, while the magnetic moment of the surface layer was rather insensitive. This was because the electron rearrangement from the t 2g to e g states during the transition was limited to within the minority spin due to the fully occupied majority spin state.

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“…In addition, nanowires are often subjected to mechanical strain along their axes, which sometimes destabilizes the magnetic ordering. [18][19][20][21][22][23][24][25] Thus, the magnetic properties of small iron nanowires with atomically sharp edges and the effect of axial strain on them are of fundamental interest in various fields.…”

Section: Introductionmentioning

confidence: 99%

Ab initiostudy of ferromagnetism in edged iron nanowires under axial strain

2011

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We perform first-principles simulations of the magnetic and electronic properties of ferromagnetic (FM) body-centered cubic (bcc) iron nanowires with characteristic sharp edges consisting of (110) and (110) surfaces and their response to mechanical strain. An enhanced magnetic moment of 2.83μ B is obtained at the edge of the FM nanowire. This enhancement originates from rearrangement of d electrons from the minority-spin t 2g state to the majority-spin t 2g state due to a significant reduction in the number of nearest-neighbor atoms at the edge. The FM phase is the most energetically favorable phase in the nanowire even under relatively high axial strains, whereas the corresponding bulk material exhibits a FM-to-antiferromagnetic transition under the same loading conditions. During tension, a discontinuous change in the magnetic moment is observed at the surface and inside the nanowire due to a bcc-face-centered-cubic structural transition. In contrast, the magnetic moment at the edge is insensitive to applied strain. This is because the majority-spin state is fully occupied at the edge, which restricts the t 2g -e g electron rearrangement to just the minority-spin state.

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Ab initiostudy of Co and Ni under uniaxial and biaxial loading and in epitaxial overlayers

Cited by 27 publications

References 71 publications

Ab initiostudy of spin-spiral noncollinear magnetism in a free-standing Fe(110) monolayer under in-plane strain

Ab initiostudy of spin-spiral noncollinear magnetism in a free-standing Fe(110) monolayer under in-plane strain

Ab initiostudy of magnetism at iron surfaces under epitaxial in-plane strain

Ab initiostudy of ferromagnetism in edged iron nanowires under axial strain

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