Results 1 - 10 of 330
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[en] The critical exponent behavior of LaCr_0_._3Mn_0_._7O_3 compound in the vicinity of ferromagnetic transition was studied by measuring isothermal dc magnetization and by analyzing them in terms of modified Arrott plot method. The critical exponents β, γ and δ corresponding to the spontaneous magnetization, initial magnetic susceptibility and isothermal magnetization with T_C=186 K were determined to be 0.325±0.006, 1.247±0.066 and 4.823±0.004 respectively and are found to be comparable to the values predicted by 3D Ising model. The obtained result is discussed in terms of presence of strong magnetic anisotropy. - Highlights: • We have reported the critical exponent study of LaCr_0_._3Mn_0_._7O_3 compound. • It was analyzed in terms of modified Arrott plot method. • The estimated values of β, γ and δ are found to be close to 3D Ising model values.
[en] In this paper a Preisach-type model, named Preisach model for patterned media (PMPM, or PM2), that successfully describes magnetization processes in structured particulate ferromagnetic media and in strongly correlated particulate media is presented. The PM2 provides explicit expressions for the magnetization curves, which makes it numerically very efficient. It obeys the exact wiping-out property and describes non-congruent minor hysteresis loops measured within given field limits
[en] In this paper, we obtain information about the topological structure of the energy landscape of the random-field Ising model by numerical simulations. We define and construct a suitable map (one-loop map) for the representation of generic metastable state. We show that the properties of this map are strictly related to the possibility of generating State by a field history
[en] A simple lattice model that allows hysteresis loops with exchange bias to be reproduced is presented. The model is based on the metastable random field Ising model, driven by an external field, with synchronous local relaxation dynamics. The key ingredient of the model is that a certain fraction f of the exchange constants between neighbouring spins is enhanced to a very large value JE. The model allows the dependence of several properties of the hysteresis loops to be analysed as a function of different parameters and we have carried out an analysis of the first-order reversal curves
[en] Neutron scattering and simulation line shape data show evidence for fractal structure from spanning clusters in the d=2 and 3 random-field Ising models as realized in dilute antiferromagnets
[en] A spin-((3)/(2)) random-field Ising model with a crystal field on the honeycomb lattice is studied within the framework of the effective-field theory with correlations. We have investigated the effect of the crystal field on the phase diagrams, magnetizations, quadrupolar moments of the system. The phase diagram exhibits a rich variety of behaviors: the reentrant phenomena and the existence of tricritical points
[en] We give an exact formulation of a mixed spin-1 and spin-3/2 Ising model on the Bethe lattice, which shows ferrimagnetism and compensation points. The model incorporates antiferromagnetic nearest-neighbor interaction which is relevant to describe ferrimagnetism. The influence of two sublattice crystal fields, D A and D B, on compensation points is studied in detail. For certain crystal-field values, the single or double compensation temperature may occur in the present system
[en] Domain walls in random-field Ising magnets can be investigated in groundstates into which walls are induced by prepared boundary conditions. We outline recent progress, and new results on (domain wall) wetting in random field systems. This is studied in fixed disorder configurations in the presence of an external field, which is varied
[en] We investigate the dynamic critical exponent of a two-dimensional Ising model defined on a curved surface with a constant negative curvature. By means of the short-time relaxation method, we find that a non-zero curvature of the underlying surface engenders a quantitative alternation of the dynamic exponent from the known value for the planar Ising model. This indicates the occurrence of a novel dynamic universality class of the Ising model induced by the negative surface curvature
[en] In this paper we present a theoretical study of size effects during relaxation in spin transition solids. The systems are described using an Ising-like model consisting of molecules having two energy levels and fictitious spin values of +1, (HS) and -1 (LS). We compare relaxation in various 2D or 3D systems (rectangular, hexagonal or cubic) and we realise an exhaustive analysis of the parameters that influence the relaxation in small size samples. The differences between homogenous and inhomogeneous systems reflected on the shapes of relaxation curves are discussed and analysed.