Young-Joon Song, K. -W. Lee
BaRuO3 having five different crystal structures has been synthesized by varying the pressure while sintering. Contrary to the other phases being nonmagnetic, the cubic perovskite phase synthesized recently shows itinerant ferromagnetic character. We investigated this ferromagnetic BaRuO3 using first principles calculations. A few van Hove singularities appear around the Fermi energy, causing unusually high magnetovolume effects of $\Delta M/\Delta a$ ~ 4.3 $\mu_B$/\AA as well as the Stoner instability [IN(0)~1.2]. At the optimized lattice parameter a, the magnetic moment M is 1.01 $\mu_B$ in the local spin density approximation. When spin-orbit coupling is included, the topology of some Fermi surfaces is altered, and the moment is reduced by 10% to a value very close to the experimentally observed value of ~ 0.8 $\mu_B$. Our results indicate that the ferromagnetism is induced by the Stoner instability, but the combined effects of magnetovolume and spin-orbit coupling determine the net moment. In addition, we briefly discuss the results of the tight-binding Wannier function technique.
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http://arxiv.org/abs/1207.7145
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