C. S. Hellberg

Structural, Electronic, and Magnetic Properties of MnO

We calculate the structural, electronic, and magnetic properties of MnO from first principles, using the full-potential linearized augmented planewave method, with both local-density and generalized-gradient approximations to exchange and correlation. We find the ground state to be of rhombohedrally distorted B1 structure with compression along the [111] direction, antiferromagnetic with type-II ordering, and insulating, consistent with experiment. We show that the distortion can be understood in terms of a Heisenberg model with distance dependent nearest-neighbor and next-nearest-neighbor interactions determined from first principles. Finally, we show that magnetic ordering can induce significant charge anisotropy, and give predictions for electric field gradients in the observed rhombohedrally distorted structure.

Density functional studies of single molecule magnets

Abstract A method for the calculation of the second-order anisotropy parameters of single molecular magnets from the single particle orbitals is reviewed. We combine this method with density functional calculations to predict the magnetic anisotropy parameters of several single molecule magnets: Mn 12 -acetate, Mn 10 , Co 4 , Fe 4 , Cr 1 and V 15 . Comparison with available experimental data shows that it is possible to predict these values quite accurately from density functional wavefunctions.

Elastic anomaly for Sr Ti O 3 thin films grown on Si(001)

X-ray diffraction measurements have revealed a negative Poissons ratio for

Domain ordering of strained 5 ML SrTiO3 films on Si(001)

\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_{3}

Anomalous lattice expansion of coherently strained SrTiO 3 thin films grown on Si ( 001 ) by kinetically controlled sequential deposition

thin films grown on Si(001). X-ray absorption fine-structure measurements demonstrate that this elastic anomaly is driven by the interfacial polarization of the

Ferroelectric Distortation in SrTiO3 Thin Films on Si(100) by X-ray Absorption Fine Structure Spectroscopy: Experiment and First-Principles Calculations

\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_{3}

Random registry shifts in quasi-one-dimensional adsorbate systems

layers. First-principles density-functional calculations support these conclusions. It is suggested that this phenomenon may be common for heteroepitaxial growth of materials that possess an ionic polarizability.

Elastic anomaly for SrTiO3 thin films grown on Si(001)

High resolution x-ray diffraction data indicate ordered square shaped coherent domains, ∼1200A in length, coexisting with longer, ∼9500A correlated regions in highly strained 5 ML SrTiO3 films grown on Si(001). These long range film structures are due to the Si substrate terraces defined by the surface step morphology. The silicon surface “step pattern” is comprised of an “intrinsic” terrace length from strain relaxation and a longer “extrinsic” interstep distance due to the surface miscut.