A density-functional theory of ferromagnetism in heterostructures of compound semiconductors doped with magnetic impurities is presented. The variable functions in the density-functional theory are the charge and spin densities of the itinerant carriers and the charge and localized spins of the impurities. The theory is applied to study the Curie temperature of planar heterostructures of III-V ...

The dependence of the Curie temperature T Curie on nearly hydrostatic pressure has been determined to 17 GPa for the weak itinerant ferromagnetic SrRuO 3 in both polycrystalline and single-crystalline form. T Curie is found to decrease under pressure from 162 K to 42.7 K at 17.2 GPa in nearly linear fashion at the rate dT Curie /dP ≃ −6.8 K/GPa. No superconductivity was found above 4 K in the p...

The effective exchange interactions of magnetic overlayers Fe/Cu(001) and Co/Cu(001) covered by a Cu-cap layer of varying thickness were calculated in real space from first principles. The effective two-dimensional Heisenberg Hamiltonian was constructed and used to estimate magnon dispersion laws, spin-wave stiffness constants, and overlayer Curie temperatures within the mean-field and random-p...

We consider stochastic dynamics for a spin system with mean field interaction, in which the interaction potential is subject to noisy and dissipative stochastic evolution. We show that, in the thermodynamic limit and at sufficiently low temperature, the magnetization of the system has a time periodic behavior, despite of the fact that no periodic force is applied.

The effect of short-time and long-time annealing at 250 • C on the conductivity, hole density, and Curie temperature of GaMnAs single layers and GaMnAs/InGaMnAs heterostructures is studied by in-situ conductivity measurements as well as Raman and SQUID measurements before and after annealing. Whereas the conductivity monotonously increases with increasing annealing time, the hole density and th...

A series of Sm3Fe28.12xCoxMo0.9 compounds (x50,4,8,12,14,16) have been synthesized and their magnetic properties and structures investigated by means of x-ray diffraction and magnetic measurements. It is found that substitution of Co for Fe leads to a significant increase of the Curie temperature and saturation magnetization. Even more important, for x>14 the easy magnetization direction change...

A preferred piezoelectric ceramic material is a BiFeO3—PbZrO3—PbTiO3 ternary solid solution wherein proportions of the constituent perovskite metal oxides are selected so that the material exhibits relatively high Curie temperatures above 380° C. and useful piezoelectric properties. Disciplines Ceramic Materials This patent is available at Iowa State University Digital Repository: http://lib.dr...