Spin-polarization-induced structural selectivity in Pd3X and Pt3X (X=3d) compounds.

Abstract

Spin polarization is known to lead to important magnetic and optical effects in open-shell atoms and elemental solids, but has rarely been implicated in controlling structural selectivity in compounds and alloys. Here we show that spin-polarized electronic structure calculations are crucial for predicting the correct $T\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0$ crystal structures for ${\mathrm{Pd}}_{3}X$ and ${\mathrm{Pt}}_{3}X$ compounds. Spin polarization leads to (i) stabilization of the ${L1}_{2}$ structure over the ${D0}_{22}$ structure in ${\mathrm{Pt}}_{3}\mathrm{Cr}$, ${\mathrm{Pd}}_{3}\mathrm{Cr}$, and ${\mathrm{Pd}}_{3}\mathrm{Mn}$, (ii) stabilization of the ${D0}_{22}$ structure over the ${L1}_{2}$ structure in ${\mathrm{Pd}}_{3}\mathrm{Co}$, and (iii) ordering (rather than phase separation) in ${\mathrm{Pt}}_{3}\mathrm{Co}$ and ${\mathrm{Pd}}_{3}\mathrm{Cr}$. The results are analyzed in terms of first-principles local spin density calculations.