Dielectric tensors of high-k {\it Pbnm} perovskites from first principles

Among the materials under consideration for future high-k dielectrics in MOSFET and other microelectronic devices are several perovskites having space group {\it Pbnm}. Among these are LaLuO$_3$, SrBO$_3$ (B = Zr, Hf), AScO$_3$ (A = La, Pr, Nd, Sm, Gd, Tb, Dy), and LaB$_{1/2}$Zr$_{1/2}$O$_3$ (B = Ca, Mg) (with lower symmetry), which are all compatible with growth on silicon and can have higher dielectric constants than HfO$_2$.\footnote{ D. G. Schlom, S. Guha, S. Datta, MRS Bull. {\bf 33}, 1017 (2008).}$^,$\footnote{Thin Films and Heterostructures for Oxide Electronics, S.~B.\ Ogale, Ed. (Springer, New York 2005), pp.~31-78.} Using first-principles DFT methods with ultrasoft pseudopotentials and GGA energy functionals, we compute the dielectric tensors, structural properties, and phonon spectra of these materials. We analyze the dependence of these properties on chemical composition, and compare with experiments where possible. We also focus on correlation between dielectric tensor anisotropy and octahedra rotation angles.