Spin-orbit-controlled metal–insulator transition in Sr2IrO4
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- Univ. of British Columbia, Vancouver, BC (Canada)
- Univ. of British Columbia, Vancouver, BC (Canada); Max Planck Inst. for Chemical Physics of Solids, Dresden (Germany)
- Paul Scherrer Inst. (PSI), Villigen (Switzerland). Swiss Light Source
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- The Ohio State Univ., Columbus, OH (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Max Planck Inst. for Solid State Research, Stuttgart (Germany)
- Max Planck Inst. for Solid State Research, Stuttgart (Germany); Pohang Univ. of Science and Technology (POSTECH) (Korea, Republic of)
In the context of correlated insulators, where electron–electron interactions (U) drive the localization of charge carriers, the metal–insulator transition is described as either bandwidth- or filling-controlled. Motivated by the challenge of the insulating phase in Sr2IrO4, a new class of correlated insulators has been proposed, in which spin–orbit coupling (SOC) is believed to renormalize the bandwidth of the half-filled jeff = 1/2 doublet, allowing a modest U to induce a charge-localized phase. Although this framework has been tacitly assumed, a thorough characterization of the ground state has been elusive. Furthermore, direct evidence for the role of SOC in stabilizing the insulating state has not been established, because previous attempts at revealing the role of SOC have been hindered by concurrently occurring changes to the filling. Here, we overcome this challenge by employing multiple substituents that introduce well-defined changes to the signatures of SOC and carrier concentration in the electronic structure, as well as a new methodology that allows us to monitor SOC directly. Specifically, we study Sr2Ir1-xTxO4 (T = Ru, Rh) by angle-resolved photoemission spectroscopy, combined with ab initio and supercell tight-binding calculations. This allows us to distinguish relativistic and filling effects, thereby establishing conclusively the central role of SOC in stabilizing the insulating state of Sr2IrO4. Most importantly, we estimate the critical value for SOC in this system to be λc = 0.42 ± 0.01 eV, and provide the first demonstration of a spin–orbit-controlled metal–insulator transition.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
- Grant/Contract Number:
- AC05-00OR22725
- OSTI ID:
- 1735464
- Journal Information:
- Nature Physics, Journal Name: Nature Physics Journal Issue: 3 Vol. 16; ISSN 1745-2473
- Publisher:
- Nature Publishing Group (NPG)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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