Journal ArticleDOI
Coherent potential approximation for randomly diluted uniaxial antiferromagnets : Application to Mn1−xZnxF2
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In this paper, a recently proposed CPA theory for treating randomly diluted antiferromagnets with uniaxial anisotropy is revised, and it is shown that such a procedure, which ignores dynamical effects occasioned by fluctuations in the local anisotropic field, leads to unphysical results beyond certain critical concentrations at which the theory breaks down.Abstract:
A recently proposed CPA theory (Tahir‐Kheli et al), for treating randomly diluted antiferromagnets with uniaxial anisotropy is revised. It is shown that such a procedure, which ignores dynamical effects occasioned by fluctuations in the local anisotropy field, leads to unphysical results beyond certain critical concentrations at which the theory breaks down. A study of the weakness, the relevance and validity of this theory is presented. The theory is expected to be relevant only when applied to systems with relatively small anisotropy. In fact, owing to its simplicity, within its range of validity, we apply a such CPA to analyse the behaviour of the zero‐field antiferromagnetic resonance in the mixed system of manganese and zinc fluorides as function of zinc concentration. Our results are compared with those from several recent experiments and a very good agreement is found. Moreover, the general features and complexity of an alternative CPA formalism which takes into account dynamical effects of fluctua...read more
Citations
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Book ChapterDOI
Static Thermodynamic Properties of Site-Random Magnetic Systems and the Percolation Problem
TL;DR: In this article, the authors concentrate on the site-diluted magnet, i.e., a magnetic system in which magnetic atoms are replaced by nonmagnetic atoms in increasing amounts.
Journal ArticleDOI
Raman scattering by magnetic excitations in disordered FeF2
TL;DR: Inelastic scattering of light has been used to study the magnetic excitations in antiferromagnetic FeF2 crystals disordered in two ways. as discussed by the authors investigated the magnetic dilute system Fe1-xZnxF2 as a function of the concentration x and temperature T, with x varying from zero nearly up to the percolation limit xp = 0.76.
Journal ArticleDOI
The preparation and magnetic properties of MnF2 and its mixtures with ZnF2 and CoF2
TL;DR: Water and oxygen-free Mn1-nZnnF2 and Mn 1-nConF2 have been prepared by a simplified method through the whole concentration range as discussed by the authors, and Magnetic susceptibility measurements of the powdered samples have been used to determine the Neel temperatures in association with measurements of sublattice magnetisation using neutron diffraction.
Journal ArticleDOI
Specific heat studies of randomly diluted magnets evidence for fractal properties of the infinite percolation cluster
TL;DR: In this paper, specific heat data on the system Fe p Zn 1-p L 6 (ClO 4 ) 2, which is an experimental realization of the sc, S = 1 2, diluted Ising antiferromagnet.
Journal ArticleDOI
CPA approach for randomly diluted anisotropic ferromagnets: para-spin-flop critical field
TL;DR: In this paper, the authors extended the coherent potential approximation to describe linear spin wave in diluted uniaxial ferromagnets with random interactions in both exchange and single-ion anisotropy.
References
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Journal ArticleDOI
The theory and properties of randomly disordered crystals and related physical systems
TL;DR: A review of the methods for determining the behavior of solids whose properties vary randomly at the microscopic level, with principal attention to systems having composition variation on a well-defined structure (random "alloys") can be found in this paper.
Journal ArticleDOI
Far‐Infrared Magnetic Resonance in CoF2, NiF2, KNiF3, and YbIG
TL;DR: In this paper, the authors measured the far infrared transmission spectra of a variety of magnetic insulators using the techniques of Fouriertransformation interferometry and showed that the temperature dependences of these resonances have been measured and compared with the Zener theory for the temperature dependence of the anisotropy energy.
Journal ArticleDOI
Spatially Random Heisenberg Spins at Very Low Temperatures. II. Dilute Antiferromagnet with Nearest-Neighbor Substitutional Short-Range Order
Journal ArticleDOI
Excitations in randomly diluted ferromagnets
TL;DR: In this article, an effective medium ansatz is introduced through the use of a generalization of the path coherent-potential-approximation approach introduced by Brouers et al in their study of random electronic alloys.
Journal ArticleDOI
A Measurement of Spin‐Wave Dispersion in MnF2 at 4.2°K
TL;DR: In this article, a spin wave was observed in a single crystal of MnF2 at 4.2°K by the inelastic scattering of neutrons, and the observed dispersion curves can be accurately described by spin wave theory using the following values for the parameters concerned: J1=0.32°K (ferromagnetic), J2=−1.76°K, |J3|<0.05°K and an anisotropy field at zero wave vector HA=1.06°K.