The magnetic excitations in electron-doped (Sr1−xLax)2IrO4 with x = 0.03 were measured using resonant inelastic x-ray scattering at the Ir L3 edge. Although much broadened, well defined dispersive magnetic excitations were observed. Comparing with the magnetic dispersion from the undoped compound, the evolution of the magnetic excitations upon doping is highly anisotropic. Along the antinodal direction, the dispersion is almost intact. On the other hand, the magnetic excitations along the nodal direction show significant softening. These results establish the presence of strong magnetic correlations in electron-doped (Sr1−xLax)2IrO4 with close analogies to the hole-doped cuprates, further motivating the search for high temperature superconductivity in this system.
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X.L. acknowledges financial support from MOST (No. 2015CB921302) and CAS (Grant No. XDB07020200) of China. Z.Y.M. is supported by the National Natural Science Foundation of China (Grants No. 11421092 and No. 11574359). Both X.L. and Z.Y.M. are supported by the National Thousand Young-Talents Program of China. The work at Brookhaven was supported by the U.S. Department of Energy, Division of Materials Science, under Contract No. DE-AC02-98CH10886. The work at the University of Kentucky was supported by NSF through Grant No. DMR-1265162. Use of the Advanced Photon Source was supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
The resistivity and magnetization data for our 3% doped (Sr1-xLax)2IrO4 sample, and the additional RIXS data for our undoped sample are provided in the Supplemental Material.
Liu, X.; Dean, M. P. M.; Meng, Z. Y.; Upton, M. H.; Qi, T.; Gog, T.; Cao, Y.; Lin, J. Q.; Meyers, D.; Ding, H.; Cao, Gang; and Hill, J. P., "Anisotropic Softening of Magnetic Excitations in Lightly Electron-Doped Sr2IrO4" (2016). Center for Advanced Materials Faculty Publications. 7.