Effect of frustrations on magnetism in the Ru double perovskite Sr 2 YRuO 6

摘要: Localized ${\mathrm{Ru}}^{5+}$ spins in ${\mathrm{Sr}}_{2}{\mathrm{YRuO}}_{6}$ form a fcc lattice with an antiferromagnetic (AFM) nearest-neighbor (NN) coupling $J\ensuremath{\approx}25\mathrm{meV}$ and rather low N\'eel temperature ${T}_{N}=26\mathrm{K}.$ Analysis of the electronic structure ${\mathrm{Sr}}_{2}{\mathrm{RuO}}_{4}$ results effective Heisenberg model. We have studied effect frustrations on AFM type-I spin-wave approximation. In model only NN state is unstable due to frustrations, ${T}_{N}=0.$ Stabilization occurs next-nearest-neighbor I or magnetic anisotropy D. Very small values $D/J\ensuremath{\sim}I/Jl~{10}^{\ensuremath{-}3}$ are enough obtain experimental ${T}_{N}$ sublattice magnetization $m=1.85{\ensuremath{\mu}}_{B}/\mathrm{Ru}$ (62% from nominal $S=3/2$ value).