Magnetism and spin-orbit coupling in Ir-based double perovskites La2−xSrxCoIrO6

Abstract

We have studied Ir spin and orbital magnetic moments in the double perovskites La2−xSrxCoIrO6 by x-ray magnetic circular dichroism. In La2CoIrO6, Ir 4+ couples antiferromagnetically to the weak ferromagnetic moment of the canted Co 2+ sublattice and shows an unusually large negative total magnetic moment (-0.38 µB/f.u.) combined with strong spin-orbit interaction. In contrast, in Sr2CoIrO6, Ir 5+ has a paramagnetic moment with almost no orbital contribution. A simple kinetic-energy-driven mechanism including spin-orbit coupling explains why Ir is susceptible to the induction of substantial magnetic moments in the double perovskite structure.

Competition between heavy fermion and Kondo interaction in isoelectronic A-site-ordered perovskites

“…2) [9,11]. This value is similar to that found in several other iridate compounds and signifies a large spin-orbit coupling (SOC) as expected for a 5d compound [9,11,37,38]. Overall, the Ir L edge data is in excellent agreement with the Cu L edge data stating the d 9 Cu 2+ ground state, with a much smaller d 8 contribution compared to the Rh and Co compounds; thus, in the CCIrO compound the hole is now almost entirely transferred from the Cu 3d -O 2p state to the Ir 5d -O 2p hybridized orbital.…”

Compensation temperatures and exchange bias inLa1.5Ca0.5CoIrO6

“…and using the standard magnetic moments of Ir 4+ (1.73 μ B ), HS Co 2+ (5.2 μ B ) and HS Co 3+ (5.48 μ B ), yields The difference to the experimental value may be related to spin-orbit coupling (SOC) on Co ions, as already reported for similar compounds [14,27]. Figure 2(a) presents the ZFC-FC magnetization curves for H dc = 500 Oe, were two peaks can be clearly observed.…”

“…We recently reported the structural and magnetic characterization of the La 2−x Ca x CoIrO 6 double perovskite series [13]. For La 2 CoIrO 6 , the transition-metal ions valences are reported to be Co 2+ and Ir 4+ [14]. Our results show that La 3+ to Ca 2+ substitution leads to Co valence changes, and La 1.5 Ca 0.5 CoIrO 6 presents both Co 2+ and Co 3+ in high-spin configuration.…”

Strong ferromagnetism induced by canted antiferromagnetic order in double perovskite iridates(La1−xSrx)2ZnIrO6Zhu1, Lu2, Wei3 et al. 2015Phys. Rev. B525120View full textAdd to dashboardCite

“…While there has been considerable work in exploring and understanding novel magnetic properties of other iridates (e.g., pyrochlores [14][15][16][17][18][19][20], honeycomb lattice [5,[21][22][23][24], and perovskites [25][26][27][28]), the highly localized double perovskites A 2 BIrO 6 have been much less intensively studied [29][30][31][32][33][34][35][36][37][38] and their magnetic properties remain to be fully understood. Using the prototypical La 2 ZnIrO 6 as an example, magnetic susceptibility measurement indicates a paramagnetic (PM)-to-ferromagnetic (FM)-like transition around 7.5 K [29,31], however, recent density functional theory calculations suggest that the low-temperature ground state should be canted antiferromagnetism instead of FM order [39].…”