Spin-orbit coupling controlled ground states in the double perovskite iridates $$\textit{A}_2\textit{B}$$IrO$$_6$$ ($$\textit{A}$$ = Ba, Sr; $$\textit{B}$$ = Lu, Sc)

Journal Article · Mon Sep 19 00:00:00 EDT 2022 · Physical Review Materials

DOI:https://doi.org/10.1103/physrevmaterials.6.094409· OSTI ID:1892414

Aczel, Adam A. ^[1]; Chen, Q. ^[2]; Clancy, J. P. ^[3]; dela Cruz, Clarina R. ^[1]; Reig-i-Plessis, D. ^[4]; MacDougall, G. J. ^[4]; Pollock, C. J. ^[5]; Upton, M. H. ^[6]; Williams, Travis J. ^[1]; LaManna, N. ^[7]; Carlo, J. P. ^[7]; Beare, J. ^[3]; Luke, G. M. ^[3]; Zhou, H. D. ^[2]

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1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2. Univ. of Tennessee, Knoxville, TN (United States)
3. McMaster Univ., Hamilton, ON (Canada)
4. Univ. of Illinois at Urbana-Champaign, IL (United States)
5. Cornell Univ., Ithaca, NY (United States)
6. Argonne National Lab. (ANL), Lemont, IL (United States). Advanced Photon Source (APS)
7. Villanova Univ., PA (United States)

Iridates with the 5$d^4$ electronic configuration have attracted recent interest due to reports of magnetically ordered ground states despite longstanding expectations that their strong spin-orbit coupling would generate a $$\textit{J}$$ = 0 electronic ground state for each Ir⁵⁺ ion. The major focus of prior research has been on the double perovskite iridates Ba₂YIrO₆ and Sr₂YIrO₆, where the nature of the ground states (i.e., ordered vs nonmagnetic) is still controversial. Here, in this work, we present neutron powder diffraction, high-energy-resolution fluorescence-detected x-ray absorption spectroscopy (HERFD-XAS), resonant inelastic x-ray scattering (RIXS), magnetic susceptibility, and muon spin relaxation data on the related double perovskite iridates Ba₂LuIrO₆, Sr₂LuIrO₆, Ba₂ScIrO₆, and Sr₂ScIrO₆ that enable us to gain a general understanding of the electronic and magnetic properties for this family of materials. Our HERFD-XAS and RIXS measurements establish $$\textit{J}$$ = 0 electronic ground states for the Ir⁵⁺ ions in all cases, with similar values for Hund's coupling $$J_H$$ and the spin-orbit coupling constant $$λ_{\text{SOC}}$$. Our bulk susceptibility and muon spin relaxation data find no evidence for long-range magnetic order or spin freezing, but they do exhibit weak magnetic signals that are consistent with extrinsic local moments. Our results indicate that the large $$λ_{\text{SOC}}$$ is the key driving force behind the electronic and magnetic ground states realized in the $5d^4$ double perovskite iridates, which agrees well with conventional wisdom.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States); Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR)
• Sponsoring Organization: National Science Foundation (NSF); Natural Sciences and Engineering Research Council of Canada (NSERC); USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF)
• Grant/Contract Number: AC02-06CH11357; AC05-00OR22725
• OSTI ID: 1892414
• Alternate ID(s): OSTI ID: 2572620
• Journal Information: Physical Review Materials, Journal Name: Physical Review Materials Journal Issue: 9 Vol. 6; ISSN 2475-9953
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
dilution refrigerator
magnetic susceptibility
magnetism
muon spin relaxation & rotation
neutron diffraction
structural properties
susceptibility measurements