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

  • Paris E Photon Science Division, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland; eugenio.paris@psi.ch thorsten.schmitt@psi.ch.
  • Tseng Y Photon Science Division, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
  • Pärschke EM Department of Physics, University of Alabama at Birmingham, Birmingham, AL 35294.
  • Zhang W Photon Science Division, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
  • Upton MH Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439.
  • Efimenko A European Synchrotron Radiation Facility, 38043 Grenoble, France.
  • Rolfs K Neutrons and Muons Research Division, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
  • McNally DE Photon Science Division, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
  • Maurel L Department of Materials, Laboratory for Mesoscopic Systems, ETH Zurich, 8093 Zurich, Switzerland.
  • Naamneh M Photon Science Division, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
  • Caputo M Photon Science Division, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
  • Strocov VN Photon Science Division, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
  • Wang Z Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, 315201 Ningbo, China.
  • Casa D Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439.
  • Schneider CW Laboratory for Multiscale Materials Experiments, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland.
  • Pomjakushina E Neutrons and Muons Research Division, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
  • Wohlfeld K Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, PL-02093 Warsaw, Poland.
  • Radovic M Photon Science Division, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
  • Schmitt T Photon Science Division, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland; eugenio.paris@psi.ch thorsten.schmitt@psi.ch.
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  • 2020-09-22
Published in:
  • Proceedings of the National Academy of Sciences of the United States of America. - 2020
elementary excitations
magnetoelastic coupling
resonant inelastic X-ray scattering
spin–orbit coupling
strain engineering
English 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.
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https://sonar.ch/global/documents/185257
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