Aspects of spin dynamics and magnetic interactions

Antropov, Vladimir; Harmon, B. N.; Смирнов, А. Н.

doi:10.1016/s0304-8853(99)00425-4

Cited by 98 publications

(88 citation statements)

References 36 publications

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“…20 The ab initio treatment of the noncollinear magnetic structure of an evolving fluid has remained a challenging task in atomic scale theory, and most investigations still focus on the magnetism of static configurations. [23][24][25][26][27][28][29][30] In our work, the calculated magnetic correlation function shows a good agreement with results from elastic neutron scattering. 20 The present work complements our previous study in two ways.…”

Section: Introductionsupporting

confidence: 72%

Noncollinear magnetism in liquid oxygen: A first-principles molecular dynamics study

Oda

Pasquarello

2004

Phys. Rev. B

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We perform first-principles molecular dynamics of liquid oxygen in which the magnetic structure evolves according to a generalized density-functional scheme allowing for noncollinear spin configurations. We investigate both structural correlations between the orientations of the molecular axes and magnetic correlations between the orientations of the molecular magnetic moments, demonstrating a clear relation between the local molecular configuration and the relative magnetic arrangement. The nuclear structure factor obtained from the simulation is found to agree well with the experimental one. The calculated magnetic structure factor shows antiferromagnetic correlations between molecules in the first shell, in accord with spin-polarized neutron scattering measurements. We observe the formation of dynamically coupled molecules, known as O 4 units, in which the molecular moments are aligned in an antiferromagnetic fashion. An analysis based on the life time of such units, revealed that in most cases the O 4 units occur as transient configurations during collisions. However, we also observed a small fraction of O 4 units surviving for relatively long periods. To account for electronic excitations which are missed in our density-functional scheme, we complement our description with a mean field model for the thermal fluctuations of the magnetic structure. The combined scheme is found to improve the description of the magnetic neutron structure factor and allows us to study the dependence of the magnetic susceptibility on temperature.

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Section: Introductionsupporting

confidence: 72%

Noncollinear magnetism in liquid oxygen: A first-principles molecular dynamics study

Oda

Pasquarello

2004

Phys. Rev. B

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“…We focus on the total effective exchange J 0 = j J ij and the interlayer exchange J z = j J ij , where the prime restricts the summation to sites j in the Fe II layer that is adjacent to the one containing site i. Figure 1 shows J 0 and J z calculated as a function of the Fermi energy E F in the rigid-band model [29]; the upper axis shows the band filling N , which is the electron count per formula unit, referenced from pure Fe 2 P. It is seen that J 0 increases smoothly by about 30% at N ∼ 1, which corresponds to a 50% substitution of all Fe atoms by Co. In a real alloy, J 0 is not expected to increase as much, because alloying with Co reduces the magnetic moments.…”

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confidence: 99%

Tunable dimensional crossover and magnetocrystalline anisotropy in Fe2P -based alloys

Журавлев

Antropov

Vishina

et al. 2017

Phys. Rev. Materials

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“…Within the linear-response approximation this problem of the ALDA has been noticed previously in Ref. [9]. The absence of spin dynamics for localized moments is another deficiency of the ALDA.…”

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confidence: 91%

Spin Currents and Spin Dynamics in Time-Dependent Density-Functional Theory

2001

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We derive and analyze the equation of motion for the spin degrees of freedom within time-dependent spin-density-functional theory (TD-SDFT). The results are (i) a prescription for obtaining many-body corrections to the single-particle spin currents from the Kohn-Sham equation of TD-SDFT, (ii) the existence of an exchange-correlation (xc) torque within TD-SDFT, (iii) a prescription for calculating, from TD-SDFT, the torque exerted by spin currents on the spin magnetization, (iv) a novel exact constraint on approximate xc functionals, and (v) the discovery of serious deficiencies of popular approximations to TD-SDFT when applied to spin dynamics. DOI: 10.1103/PhysRevLett.87.206403 PACS numbers: 71.15.Mb, 72.25. -b, 73.40. -c, 75.40.Gb The dynamics of the spin degrees of freedom is responsible for such diverse phenomena as spin wave excitations, Bloch wall motion, spin-polarized currents, spin injection, and spin filtering; concepts and phenomena which are important, e.g., in the growing field of spintronics [1]. The calculation of spin dynamics within density-functional theory (DFT) has consequently received much attention [2]. The most popular DFT method for a first-principles treatment of the spin degrees of freedom is spin-densityfunctional theory (SDFT, see Refs. [3,4] for reviews.) SDFT has led to versatile and powerful schemes for the calculation of, e.g., total energies, spin densities, and spin-resolved single-particle band structures, but its traditional (i.e., ground state) formulation is applicable only to static situations. This situation has changed with the advent of time-dependent DFT (TD-DFT) [5], which has brought dynamical phenomena within reach of DFT.In this Letter, we first derive the equation of motion for the spin magnetization from TD-SDFT, including exchange-correlation (xc) effects. We then show how this equation can be used to obtain information on the manybody spin current. Although one might think that a calculation of spin currents would require the more complex formalism of time-dependent current-density-functional theory (CDFT), we find that this is not entirely true: as a consequence of the continuity equation TD-SDFT suffices to calculate the spin currents in several cases of great practical interest.Numerical applications of TD-SDFT, as of any other DFT, require knowledge of the xc potentials, which contain all many-body effects beyond the Hartree approximation. In traditional DFT many exact properties of these xc potentials are known, and greatly aid the construction of good approximations [3,4], but the same is not true in the time-dependent case, where properties of the xc potentials are just beginning to be explored [6]. As a by-product, our analysis reveals a previously unknown exact property of the xc potentials of TD-SDFT, which strongly constrains suitable approximations.In TD-SDFT the fundamental variables are the timedependent particle density,and the time-dependent magnetization (or spin) densitywhere C C͑r 1 , . . . , r N , t͒ is the many-body wave function (spin ...

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Aspects of spin dynamics and magnetic interactions

Cited by 98 publications

References 36 publications

Noncollinear magnetism in liquid oxygen: A first-principles molecular dynamics study

Noncollinear magnetism in liquid oxygen: A first-principles molecular dynamics study

Tunable dimensional crossover and magnetocrystalline anisotropy in Fe2P -based alloys

Spin Currents and Spin Dynamics in Time-Dependent Density-Functional Theory

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