Crossover from coherent to incoherent scattering in spin-orbit dominated   Sr2IrO4
  Strong spin-orbit interaction in the two dimensional compound Sr2IrO4 leads to the formation of Jeff=1/2 isospins with unprecedented dynamics. In Raman scattering a continuum attributed to double spin scattering is observed. With higher excitation energy of the incident Laser this signal crosses over to an incoherent background. The characteristic energy scale of this cross over is identical to that of intensity resonance effects in phonon scattering. It is related to exciton-like orbital excitations that are also evident in resonant X-Ray scattering. The crossover and evolution of incoherent excitations are proposed to be due to their coupling to spin excitations. This signals a spin-orbit induced entanglement of spin, lattice and charge degrees of freedoms in Sr2IrO4. 
Mehmet Fatih Cetin, Peter Lemmens, Vladimir Gnezdilov, Dirk   Wulferding, Dirk Menzel, Tomohiro Takayama, Kei Ohashi, and Hi...
cond-mat.str-el cond-mat.supr-con