Fluctuations Of Molecular Field Research Articles

Spatial Dependence of Magnetization and Gaussian Fluctuations of Molecular Field in an Ising Nanopyramid Interacting with the Substrate

We study thermodynamic properties of an Ising model of a ferromagnetic nanoscopic pyramid deposited on a ferromagnetic bulk substrate. The influence of the interaction between the pyramid and the substrate is calculated in terms of the reduced-state (density) operator used for description of thermodynamic properties of nanoscopic systems. The spatial distribution of magnetization in the nanopyramid is obtained in the Gaussian fluctuations approximation.

Spatial distribution of Gaussian fluctuations of the molecular field and magnetization in the pyramid-like Ising nanoscopic system interacting with the substrate

We study thermodynamic properties of an Ising model of a ferromagnetic nanoscopic pyramid deposited onto a ferromagnetic bulk substrate. The influence of the interaction between the pyramid and the substrate is calculated in terms of the equilibrium reduced-state (density) operator used for description of thermodynamic properties of nanoscopic systems. The spatial distribution of the fluctuations of molecular field and magnetization in the nanoscopic pyramid is obtained in the Gaussian fluctuations approximation. Experimental consequences for the magnetic force measurements are briefly discussed.

The Influence of Non-Magnetic Substrate on Spatial Distribution of Gaussian Fluctuations of Molecular Field in Magnetic Nanoparticles and Ultrathin Films

An Ising (S = 1) model of ferromagnetic nanoparticles and ultrathin films of the sc structure deposited on a non-magnetic substrate is considered. The substrate was assumed to affect the crystal field around the atoms lying closest to it. Consequently, the one-ion anisotropy constant of spin moments of these atoms becomes dependent on the appropriate component of the tensor of the magnetic structure deformation. This dependence was assumed to be linear. To obtain approximations of the Gaussian fluctuations of molecular field, the generalised equilibrium reduced density operator, along with the Feynman diagram technique were used. As a result, temperature dependences of the spatial distributions of mean fluctuations of the magnetic field versus the changes in the one-ion anisotropy constant induced by the non-magnetic substrate were obtained. PACS numbers: 75.10.Hk, 75.70.—i

Gaussian Fluctuations of Molecular Field in Quasi-One-Dimensional Ising Model

Quasi-one-dimensional spin systems described by an Ising-like Hamiltonian with a strong space anisotropy (s = 1/2) are investigated. Magnetic properties of this model are examined in the approximation including Gaussian fluctuations of molecular field. This paper reports an attempt at obtaining more accurate results for Gaussian fluctuation of molecular field by an exact formula for mean fluctuations of a spin.

Magnetic properties of quasi-low-dimensional Ising models

Quasi-low-dimensional spin systems described by an Ising-like Hamiltonian with a strong space anisotropy ( s = 1 2 ) are investigated. Magnetization and susceptibility of this model are examined in the approximation including Gaussian fluctuations of molecular field. This communication reports an attempt to obtain more accurate results for Gaussian fluctuation of molecular field by an exact formula for mean fluctuations of a spin.

On the influence of molecular field spatial fluctuations on the low temperature properties of PdFe-like alloys

The fluctuations of molecular field in the PdFe-like alloys due to random distribution of the impurities have been shown to give a contribution to the specific heat and magnetization, which can compete with the contribution of spin waves.