Spin-Polarization-Induced Structural Selectivity inPd3XandPt3X(X=3d) Compounds

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 $T=0\mathrm{}$ crystal structures for ${\mathrm{Pd}}_{3}X$ and ${\mathrm{Pt}}_{3}X$ compounds. Spin polarization leads to (i) stabilization of the ${L1\mathrm{}}_2$ structure over the ${D0\mathrm{}}_{22}$ structure in ${\mathrm{Pt}}_3\mathrm{Cr}$, ${\mathrm{Pd}}_3\mathrm{Cr}$, and ${\mathrm{Pd}}_3\mathrm{Mn}$, (ii) stabilization of the ${D0\mathrm{}}_{22}$ structure over the ${L1\mathrm{}}_2$ 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.