Fig. 1: Instantaneous photo-doping response of magnetic order in Sr2IrO4.
From: Decoupling of static and dynamic criticality in a driven Mott insulator
a Schematic of an IrO2 layer (O: red; Ir: orange; Sr: gray spheres). Azure squares represent the ab-plane projection of the IrO6 octahedra and gray arrows represent the Jeff = 1/2 pseudospins. Each IrO2 layer, shown as blue planes at z = 0, 1/4, 2/4, 3/4, with z the fractional coordinate along the c-axis, possesses a net moment (red arrow) due to pseudospin canting, which is staggered along the c-axis. b Schematic of the time-resolved second harmonic generation rotational anisotropy (SHG-RA) setup (See “Time-resolved spectroscopic probes”). Wavelengths of the pump pulse and incident and SHG probe pulses are color-coded. Curved black arrows indicate co-rotating optical elements. Data shown throughout the manuscript are acquired in the Pin-Sout polarization channel. Different colors on the sample represent distinct magnetic domains. Inset: schematic of n-type photo-doping and resulting doublon generation and propagation through the antiferromagnetic lattice (red line). DOS density of states, LHB (UHB) lower (upper) Hubbard band, EF Fermi energy. c Temperature dependence of the change in SHG intensity ΔI(2ω) relative to T = 300 K for an un-pumped sample acquired at the angle of maximum intensity (red shaded lobe in the SHG-RA plots). The red dashed line is a guide to the eye and the vertical dashed line marks the Néel temperature (TN). Vertical error bars represent the range of intensity values obtained upon selecting different regions of the CCD camera for radial integration and background subtraction in order to convert raw data into SHG-RA intensity patterns. d Pump fluence dependence of ΔI(2ω) at t = 0 and T = 80 K with corresponding SHG-RA patterns (white circles). Fits to the data below (above) Fc including both electric-quadrupole (EQ) and surface magnetization-induced electric-dipole (SMIED) terms (solely EQ term) are overlaid (black lines). Height of the gray bar represents the change in EQ SHG intensity with respect to the equilibrium value as discussed in the main text. Horizontal error bars represent an upper bound on the uncertainty in the calculation of nex assuming F = 2 mJ/cm2 (as described in “Conversion from F to nex”). The SHG-RA intensities are normalized to the T = 300 K value (circular grid scale).
