Isotropic and anisotropic regimes of the spin-dynamics in Sr$_{2}$IrO$_{4}$ : Field-dependent Raman scattering study

Experimental studies of the strong spin-orbit coupled material, Sr$_{2}$IrO$_{4}$, have provided evidence that the spin dynamics of this material can be described by an isotropic two-dimensional effective Heisenberg description. To study how well this description describes the spin-dynamics of Sr$_{2}$IrO$_{4}$ in different magnetic field regimes, in this talk, we present field-dependent Raman scattering studies of the low-energy spin-dynamics in Sr$_{2}$IrO$_{4}$. We find that for H\textgreater 1.5 T, the spin-dynamics of Sr$_{2}$IrO$_{4}$ are well described by an isotropic, 2D description. However, at low fields, H\textless 1.5 T, the spin dynamics show evidence for the effects of in-plane anisotropy and interlayer coupling. These effects must therefore be considered when modeling the low-field magnetic and dynamical properties of Sr$_{2}$IrO$_{4}$.