Magnetic frustration in the cubic double perovskite <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">Ba</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">NiIrO</mml:mi><mml:mn>6</mml:mn></mml:msub></mml:math>

Hybrid transition metal oxides continue to attract attention due their multiple degrees of freedom ($e.g.$, lattice, charge, spin, and orbital) versatile properties. Here we investigate the magnetic electronic properties newly synthesized double perovskite Ba$_2$NiIrO$_6$, using crystal field theory, superexchange model analysis, density functional calculations, parallel tempering Monte Carlo (PTMC) simulations. Our results indicate that Ba$_2$NiIrO$_6$ has Ni$^{2+}$ ($t_{2g}^{6}e_{g}^{2}$)-Ir$^{6+}$ ($t_{2g}^{3}$) charge states. The first nearest-neighboring (1NN) Ni$^{2+}$-Ir$^{6+}$ ions prefer a ferromagnetic (FM) coupling as expected from Goodenough-Kanamori-Anderson rules, which contradicts experimental antiferromagnetic (AF) order in Ba$_2$NiIrO$_6$. We find strong 2NN AF couplings are frustrated fcc sublattices, they play major role determining observed ground state. also prove $J_{\rm eff}$ = 3/2 1/2 states induced by spin-orbit coupling, would be manifested low-dimensional (e.g., layered) iridates, however not case for cubic PTMC simulations show when long-range (2NN 3NN) interactions included, an with $T_{\rm N}$ 66 K obtained it is well comparable 51 K. Meanwhile, propose possible 2$\times$2$\times$2 noncollinear structure