Influence of structural distortions on the Ir magnetism in Ba2−xSrxYIrO6 double perovskites

Abstract

We explore the relative strengths of spin orbit coupling and crystal field splitting in the Ir 5+ compounds Ba 2-x Sr x YIrO 6 . In the case of strong spin orbit coupling and regular Ir 5+ octahedra, one expects a nonmagnetic J = 0 state; in the case of distorted octahedra where crystal field effects dominate, the t 2g manifold splits into a magnetic ground state. We report the results of continuously transitioning from the cubic Ba 2 YIrO 6 double perovskite with ideal octahedra to the monoclinic Sr 2 YIrO 6 double perovskite with distorted octahedra. We see no emergence of an enhanced Ir 5+ magnetic moment in the series on increasing the structural distortions, as would have been the case for significant crystal field splitting. The near-constant magnetic moment observed through the Ba 2-x Sr x YIrO 6 series reinforces the notion that spin-orbit coupling is the dominant force in determining the magnetism of iridium-oxygen octahedra in perovskitelike structures.

Iridium double perovskite Sr2YIrO6 : A combined structural and specific heat study

“…Our results are in strong contrast with the reported ones by Cao et al [20], but in full agreement with recent reports on polycrystalline samples [23,24], pointing towards a nonmagnetic ground state with the presence of a small amount of correlated J = 1/2 impurities.…”

“…More recent works on polycrystalline samples of the series Ba 2−x Sr x YIrO 6 [23,24] did not observe any signature for long-range magnetic order in this material in their magnetic susceptibility characterization, in strong contrast with Cao et al [20]. On the contrary, these reports reinforce the notion of a nonmagnetic ground state dominated by strong SOC.…”

“…On the contrary, these reports reinforce the notion of a nonmagnetic ground state dominated by strong SOC. In both reports [23,24] the magnetic characteristics of the system do not change significantly across the series, and the effective magnetic moment per Ir is much less than the value expected for an S = 1 system as reported by Cao et al [20], demonstrating a strongly SOC dominated ground state.…”

Density matrix renormalization group study of a three-orbital Hubbard model with spin-orbit coupling in one dimension

“…More recently, interest also developed in other transition metal oxides with octahedron or distorted octahedron crystal-field splittings leading to (t 2g ) 4 ions [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. When the Hubbard U and Hund J H couplings are large it is expected that the system develops S = 1 states, while increasing the SOC λ should lead to states with an effective angular momentum zero.…”

Diluted paramagnetic impurities in nonmagnetic Ba2YIrO6

“…16 In contrast, studies on polycrystals of the series Ba 2−x Sr x YIrO 6 reported the absence of any long-range order and no significant change in the magnetic properties upon increasing the structural disorder from cubic Ba 2 YIrO 6 with regular IrO 6 octahedra to monoclinic Sr 2 YIrO 6 with highly distorted IrO 6 octahedra, thus demonstrating that the CF splitting in Sr 2 YIrO 6 is not enough to compete with the strong spin-orbit coupling. 19,20 A recent detailed single crystal x-ray diffraction analysis of Sr 2 YIrO 6 even questioned the formerly reported monoclinic structure 15,19,21 but reported a cubic unit cell with regular IrO 6 octahedra.…”