Abstract
Measuring how the magnetic correlations evolve in doped Mott insulators has greatly improved our understanding of the pseudogap, non-Fermi liquids and high-temperature superconductivity1,2,3,4. Recently, photo-excitation has been used to induce similarly exotic states transiently5,6,7. However, the lack of available probes of magnetic correlations in the time domain hinders our understanding of these photo-induced states and how they could be controlled. Here, we implement magnetic resonant inelastic X-ray scattering at a free-electron laser to directly determine the magnetic dynamics after photo-doping the Mott insulator Sr2IrO4. We find that the non-equilibrium state, 2 ps after the excitation, exhibits strongly suppressed long-range magnetic order, but hosts photo-carriers that induce strong, non-thermal magnetic correlations. These two-dimensional (2D) in-plane Néel correlations recover within a few picoseconds, whereas the three-dimensional (3D) long-range magnetic order restores on a fluence-dependent timescale of a few hundred picoseconds. The marked difference in these two timescales implies that the dimensionality of magnetic correlations is vital for our understanding of ultrafast magnetic dynamics.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 12 print issues and online access
$259.00 per year
only $21.58 per issue
Rent or buy this article
Prices vary by article type
from$1.95
to$39.95
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Scalapino, D. J. A common thread: the pairing interaction for unconventional superconductors. Rev. Mod. Phys. 84, 1383–1417 (2012).
Kim, Y. et al. Fermi arcs in a doped pseudospin-1/2 Heisenberg antiferromagnet. Science 345, 187–190 (2014).
Cao, Y. et al. Hallmarks of the Mott-metal crossover in the hole doped pseudospin-1/2 Mott insulator Sr2IrO4 . Nature Commun. 7, 11367 (2016).
de la Torre, A. et al. Collapse of the Mott gap and emergence of a nodal liquid in lightly doped Sr2IrO4 . Phys. Rev. Lett. 115, 176402 (2015).
Fausti, D. et al. Light-induced superconductivity in a stripe-ordered cuprate. Science 331, 189–191 (2011).
Zhang, J. & Averitt, R. Dynamics and control in complex transition metal oxides. Annu. Rev. Mater. Res. 44, 19–43 (2014).
Aoki, H. et al. Nonequilibrium dynamical mean-field theory and its applications. Rev. Mod. Phys. 86, 779–837 (2014).
Kim, B. J. et al. Phase-sensitive observation of a spin-orbital Mott state in Sr2IrO4 . Science 323, 1329–1332 (2009).
Kim, J. et al. Magnetic excitation spectra of Sr2IrO4 probed by resonant inelastic X-ray scattering: establishing links to cuprate superconductors. Phys. Rev. Lett. 108, 177003 (2012).
Lee, P. A., Nagaosa, N. & Wen, X.-G. Doping a Mott insulator: physics of high-temperature superconductivity. Rev. Mod. Phys. 78, 17–85 (2006).
Wang, F. & Senthil, T. Twisted Hubbard model for Sr2IrO4: magnetism and possible high temperature superconductivity. Phys. Rev. Lett. 106, 136402 (2011).
Yan, Y. J. et al. Electron-doped Sr2IrO4: an analogue of hole-doped cuprate superconductors demonstrated by scanning tunneling microscopy. Phys. Rev. X 5, 041018 (2015).
Cao, G., Bolivar, J., McCall, S., Crow, J. E. & Guertin, R. P. Weak ferromagnetism, metal-to-nonmetal transition, and negative differential resistivity in single-crystal Sr2IrO4 . Phys. Rev. B 57, R11039–R11042 (1998).
Moon, S. J. et al. Electronic structures of layered perovskite Sr2MO4 (M = Ru, Rh, and Ir). Phys. Rev. B 74, 113104 (2006).
Ehrke, H. et al. Photoinduced melting of antiferromagnetic order in La0.5Sr1.5MnO4 measured using ultrafast resonant soft X-ray diffraction. Phys. Rev. Lett. 106, 217401 (2011).
Zhou, S. et al. Glass-like recovery of antiferromagnetic spin ordering in a photo-excited manganite Pr0.7Ca0.3MnO3 . Sci. Rep. 4, 4050 (2014).
Chuang, Y. D. et al. Real-time manifestation of strongly coupled spin and charge order parameters in stripe-ordered La1.75Sr0.25NiO4 nickelate crystals using time-resolved resonant X-ray diffraction. Phys. Rev. Lett. 110, 127404 (2013).
Caviglia, A. D. et al. Photoinduced melting of magnetic order in the correlated electron insulator NdNiO3 . Phys. Rev. B 88, 220401 (2013).
Lee, W.-S. et al. Phase fluctuations and the absence of topological defects in a photo-excited charge-ordered nickelate. Nature Commun. 3, 838 (2012).
Boeglin, C. et al. Distinguishing the ultrafast dynamics of spin and orbital moments in solids. Nature 465, 458–461 (2010).
Kampfrath, T. et al. Coherent terahertz control of antiferromagnetic spin waves. Nature Photon. 5, 31–34 (2011).
Malinowski, G. et al. Control of speed and efficiency of ultrafast demagnetization by direct transfer of spin angular momentum. Nature Phys. 4, 855–858 (2008).
Ament, L. J. P., vanVeenendaal, M., Devereaux, T. P., Hill, J. P. & van den Brink, J. Resonant inelastic X-ray scattering studies of elementary excitations. Rev. Mod. Phys. 83, 705–767 (2011).
Dean, M. P. M. Insights into the high temperature superconducting cuprates from resonant inelastic X-ray scattering. J. Magn. Magn. Mater. 376, 3–13 (2015).
Batignani, G. et al. Probing ultrafast photo-induced dynamics of the exchange energy in a Heisenberg antiferromagnet. Nature Photon. 9, 506–510 (2015).
Ishii, K. et al. Momentum-resolved electronic excitations in the Mott insulator Sr2IrO4 studied by resonant inelastic X-ray scattering. Phys. Rev. B 83, 115121 (2011).
Kim, J. et al. Excitonic quasiparticles in a spin–orbit Mott insulator. Nature Commun. 5, 4453 (2014).
Okamoto, H. et al. Ultrafast charge dynamics in photoexcited Nd2CuO4 and La2CuO4 cuprate compounds investigated by femtosecond absorption spectroscopy. Phys. Rev. B 82, 060513 (2010).
Manousakis, E. The spin-1/2 Heisenberg antiferromagnet on a square lattice and its application to the cuprous oxides. Rev. Mod. Phys. 63, 1–62 (1991).
Rønnow, H. M. et al. Spin dynamics of the 2d spin quantum antiferromagnet copper deuteroformate tetradeuterate (CFTD). Phys. Rev. Lett. 87, 037202 (2001).
Fujiyama, S. et al. Two-dimensional Heisenberg behavior of Jeff = 1/2 isospins in the paramagnetic state of the spin-orbital Mott insulator Sr2IrO4 . Phys. Rev. Lett. 108, 247212 (2012).
Vale, J. G. et al. Importance of XY anisotropy in Sr2IrO4 revealed by magnetic critical scattering experiments. Phys. Rev. B 92, 020406 (2015).
Rayan Serrao, C. et al. Epitaxy-distorted spin-orbit Mott insulator in Sr2IrO4 thin films. Phys. Rev. B 87, 085121 (2013).
Chollet, M. et al. The X-ray pump-probe instrument at the LINAC coherent light source. J. Synchrotron Radiat. 22, 503–507 (2015).
Acknowledgements
The X-ray scattering work by M.P.M.D., Y.C., V.T. and X.M.C. was supported by the US Department of Energy Basic Energy Sciences Division of Materials Science and Engineering. X.L. acknowledges financial support from MOST (No. 2015CB921302) and CAS (Grant No: XDB07020200) of China. P.J. acknowledges support by Laboratory Directed Research and Development (LDRD) Program 12-007 (Complex Modeling). J.K., D.C. and A.H.S. were supported by the US Department of Energy under Contract No. DE-AC02-06CH11357. S.W. acknowledges financial support from Spanish MINECO (Severo Ochoa grant SEV-2015-0522), Ramon y Cajal programme RYC-2013-14838, Marie Curie Career Integration Grant PCIG12-GA-2013-618487 and Fundació Privada Cellex. J.L. is sponsored by the Science Alliance Joint Directed Research and Development Program at the University of Tennessee. Work in London was supported by the EPSRC. The magnetic Bragg peak measurements were performed at the BL3 of SACLA with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal No. 2014B8018). This research made use of the Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, which is a DOE Office of Science User Facility, under Contract No. DE-AC02-76SF00515.
Author information
Authors and Affiliations
Contributions
J.P.H., X.L., M.P.M.D. and M.F. initiated and planned the project. M.P.M.D., Y.C., X.L., S.W., D.Z., R.M., V.T., X.M.C., J.G.V., D.C., J.K., A.H.S., P.J., R.A.-M., J.M.G., A.R., J.R., M.S., S.S., M.K., H.L., L.P., S.O., T.K., M.Y., Y.T., T.T., L.H., C.-L.C., D.F.M., M.F. and J.P.H. prepared for and performed the experiments. M.P.M.D., Y.C., X.L., S.W., M.F., D.F.M. and J.P.H. analysed and interpreted the data. J.L., C.R.S. and B.J.K. prepared the samples. M.P.M.D. and Y.C. wrote the paper with contributions from X.L., S.W., D.F.M., M.F. and J.P.H.
Corresponding authors
Ethics declarations
Competing interests
The authors declare no competing financial interests.
Supplementary information
Supplementary Information
Supplementary Information (PDF 436 kb)
Rights and permissions
About this article
Cite this article
Dean, M., Cao, Y., Liu, X. et al. Ultrafast energy- and momentum-resolved dynamics of magnetic correlations in the photo-doped Mott insulator Sr2IrO4. Nature Mater 15, 601–605 (2016). https://doi.org/10.1038/nmat4641
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/nmat4641
This article is cited by
-
Magnetic excitations beyond the single- and double-magnons
Nature Communications (2023)
-
Exciton-assisted low-energy magnetic excitations in a photoexcited Mott insulator on a square lattice
Communications Physics (2023)
-
A Hubbard exciton fluid in a photo-doped antiferromagnetic Mott insulator
Nature Physics (2023)
-
Witnessing light-driven entanglement using time-resolved resonant inelastic X-ray scattering
Nature Communications (2023)
-
Time, momentum, and energy resolved pump-probe tunneling spectroscopy of two-dimensional electron systems
Nature Communications (2023)