Ferromagnetic Hollandite K2Cr8O16

Elasticity of (K,Na)AlSi3O8 hollandite from lattice dynamics calculations

We compute the elastic constants tensor and the seismic properties of KAlSi3O8 and K0.8Na0.2AlSi3O8 up to the ferroelastic transition using density-functional theory and density-functional perturbation theory in the ABINIT implementation. We observe a softening of the tetragonal shear with pressure that precedes the ferroelastic transition. The Reuss shear moduli become negative at respectively...

Crystal Structure and Magnetic Properties of the Novel Hollandite Ba1.3Co1.3Ti6.7O16

Single crystals of the new barium hollandite Ba1.3Co1.3Ti6.7O16 were obtained from a BaCl2 flux (I2/m, Z = 1, a = 9.9470(4), b = 2.9714(2), c = 10.2260(5) Å, β = 90.906(2)◦). In the crystal structure piles of Ba atoms are situated within a framework of edgeand vertex-sharing octahedra (Co,Ti)O6. The composition was deduced from microprobe analyses, structure refinements and charge balance argum...

Criteria for ferromagnetic – insulator – ferromagnetic tunneling

The Rowell criteria, commonly used to identify tunneling in magnetic tunnel junctions (MTJ), are scrutinized. While neither the exponential-thickness dependence of the conductivity nor fits of non-linear transport data are found to be reliable tunneling criteria, the temperature-dependent conductivity does remain a solid criterion. Based on experimental studies of the bias and temperature-depen...

Ferromagnetic semiconductors

The current status and prospects of research on ferromagnetism in semiconductors are reviewed. The question of the origin of ferromagnetism in europium chalcogenides, chromium spinels and, particularly, in diluted magnetic semiconductors is addressed. The nature of electronic states derived from 3d of magnetic impurities is discussed in some detail. Results of a quantitative comparison between ...

Ferromagnetic resonance