Strain engineering of the charge and spin-orbital interactions in Sr2IrO4

E. Paris, Y. Tseng, E. Paerschke, W. Zhang, M.H. Upton, A. Efimenko, K. Rolfs, D.E. McNally, L. Maurel, M. Naamneh, M. Caputo, V.N. Strocov, Z. Wang, D. Casa, C.W. Schneider, E. Pomjakushina, K. Wohlfeld, M. Radovic, T. Schmitt, Proceedings of the National Academy of Sciences of the United States of America 117 (2020) 24764–24770.

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Author
Paris, Eugenio; Tseng, Yi; Paerschke, EkaterinaIST Austria ; Zhang, Wenliang; Upton, Mary H; Efimenko, Anna; Rolfs, Katharina; McNally, Daniel E; Maurel, Laura; Naamneh, Muntaser; Caputo, Marco; Strocov, Vladimir N
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Department
Abstract
In the high spin–orbit-coupled Sr2IrO4, the high sensitivity of the ground state to the details of the local lattice structure shows a large potential for the manipulation of the functional properties by inducing local lattice distortions. We use epitaxial strain to modify the Ir–O bond geometry in Sr2IrO4 and perform momentum-dependent resonant inelastic X-ray scattering (RIXS) at the metal and at the ligand sites to unveil the response of the low-energy elementary excitations. We observe that the pseudospin-wave dispersion for tensile-strained Sr2IrO4 films displays large softening along the [h,0] direction, while along the [h,h] direction it shows hardening. This evolution reveals a renormalization of the magnetic interactions caused by a strain-driven cross-over from anisotropic to isotropic interactions between the magnetic moments. Moreover, we detect dispersive electron–hole pair excitations which shift to lower (higher) energies upon compressive (tensile) strain, manifesting a reduction (increase) in the size of the charge gap. This behavior shows an intimate coupling between charge excitations and lattice distortions in Sr2IrO4, originating from the modified hopping elements between the t2g orbitals. Our work highlights the central role played by the lattice degrees of freedom in determining both the pseudospin and charge excitations of Sr2IrO4 and provides valuable information toward the control of the ground state of complex oxides in the presence of high spin–orbit coupling.
Publishing Year
Date Published
2020-10-06
Journal Title
Proceedings of the National Academy of Sciences of the United States of America
Acknowledgement
We gratefully acknowledge C. Sahle for experimental support at the ID20 beamline of the ESRF. The soft X-ray experiments were carried out at the ADRESS beamline of the Swiss Light Source, Paul Scherrer Institut (PSI). E. Paris and T.S. thank X. Lu and C. Monney for valuable discussions. The work at PSI is supported by the Swiss National Science Foundation (SNSF) through Project 200021_178867, the NCCR (National Centre of Competence in Research) MARVEL (Materials’ Revolution: Computational Design and Discovery of Novel Materials) and the Sinergia network Mott Physics Beyond the Heisenberg Model (MPBH) (SNSF Research Grants CRSII2_160765/1 and CRSII2_141962). K.W. acknowledges support by the Narodowe Centrum Nauki Projects 2016/22/E/ST3/00560 and 2016/23/B/ST3/00839. E.M.P. and M.N. acknowledge funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant Agreements 754411 and 701647, respectively. M.R. was supported by the Swiss National Science Foundation under Project 200021 – 182695. This research used resources of the APS, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract DE-AC02-06CH11357.
Volume
117
Issue
40
Page
24764-24770
ISSN
eISSN
IST-REx-ID

Cite this

Paris E, Tseng Y, Paerschke E, et al. Strain engineering of the charge and spin-orbital interactions in Sr2IrO4. Proceedings of the National Academy of Sciences of the United States of America. 2020;117(40):24764-24770. doi:10.1073/pnas.2012043117
Paris, E., Tseng, Y., Paerschke, E., Zhang, W., Upton, M. H., Efimenko, A., … Schmitt, T. (2020). Strain engineering of the charge and spin-orbital interactions in Sr2IrO4. Proceedings of the National Academy of Sciences of the United States of America, 117(40), 24764–24770. https://doi.org/10.1073/pnas.2012043117
Paris, Eugenio, Yi Tseng, Ekaterina Paerschke, Wenliang Zhang, Mary H Upton, Anna Efimenko, Katharina Rolfs, et al. “Strain Engineering of the Charge and Spin-Orbital Interactions in Sr2IrO4.” Proceedings of the National Academy of Sciences of the United States of America 117, no. 40 (2020): 24764–70. https://doi.org/10.1073/pnas.2012043117.
E. Paris et al., “Strain engineering of the charge and spin-orbital interactions in Sr2IrO4,” Proceedings of the National Academy of Sciences of the United States of America, vol. 117, no. 40, pp. 24764–24770, 2020.
Paris E, Tseng Y, Paerschke E, Zhang W, Upton MH, Efimenko A, Rolfs K, McNally DE, Maurel L, Naamneh M, Caputo M, Strocov VN, Wang Z, Casa D, Schneider CW, Pomjakushina E, Wohlfeld K, Radovic M, Schmitt T. 2020. Strain engineering of the charge and spin-orbital interactions in Sr2IrO4. Proceedings of the National Academy of Sciences of the United States of America. 117(40), 24764–24770.
Paris, Eugenio, et al. “Strain Engineering of the Charge and Spin-Orbital Interactions in Sr2IrO4.” Proceedings of the National Academy of Sciences of the United States of America, vol. 117, no. 40, National Academy of Sciences, 2020, pp. 24764–70, doi:10.1073/pnas.2012043117.
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