Glass-like recovery of antiferromagnetic spin ordering and dimensional   crossover in a photo-excited manganite Pr$_{0.7}$Ca$_{0.3}$MnO$_3$
  Electronic orderings of charges, orbitals and spins are observed in many strongly correlated electron materials, and revealing their dynamics is a critical step toward understanding the underlying physics of important emergent phenomena. Here we use time-resolved resonant soft x-ray scattering spectroscopy to probe the dynamics of antiferromagnetic spin ordering in the manganite Pr$_{0.7}$Ca$_{0.3}$MnO$_3$ following ultrafast photo-exitation. Our studies reveal a glass-like recovery of the spin ordering and a crossover in the dimensionality of the restoring interaction from quasi-1D at low pump fluence to 3D at high pump fluence. This behavior arises from the metastable state created by photo-excitation, a state characterized by spin disordered metallic droplets within the larger charge- and spin-ordered insulating domains. Comparison with time-resolved resistivity measurements suggests that the collapse of spin ordering is correlated with the insulator-to-metal transition, but the recovery of the insulating phase does not depend on the re-establishment of the spin ordering. 
S.Y. Zhou, M.C. Langner, Y. Zhu, Y.-D. Chuang, M. Rini, T.E. Glover,   M.P. Hertlein, A.G. Cruz Gonzalez, N. Tahir, Y. Tomio...
cond-mat.str-el cond-mat.mtrl-sci