Unraveling the Nature of Magnetism of the 5d(4) Double Perovskite Ba2YIrO6

作者：Fuchs S^*; Dey T; Aslan Cansever G; Maljuk A; Wurmehl S; Buechner B; Kataev V

来源：Physical Review Letters, 2018, 120(23): 237204.

DOI：10.1103/PhysRevLett.120.237204

We report electron spin resonance (ESR) spectroscopy results on the double perovskite Ba 2 YIrO6. On general grounds, this material is expected to be nonmagnetic due to the strong coupling of the spin and orbital momenta of Ir5+ (5d(4)) ions. However, controversial experimental reports on either strong antiferromagnetism with static order at low temperatures or just a weakly paramagnetic behavior have triggered a discussion on the breakdown of the generally accepted scenario of the strongly spin-orbit coupled ground states in the 5d(4) iridates and the emergence of a novel exotic magnetic state. Our data evidence that the magnetism of the studied material is solely due to a few percent of Ir4+ and Ir6+ magnetic defects while the regular Ir5+ sites remain nonmagnetic. Remarkably, the defect Ir6+ species manifest magnetic correlations in the ESR spectra at T less than or similar to 20 K, suggesting a long-range character of superexchange in the double perovskites as proposed by recent theories.

• 出版日期2018-6-8