Ultrafast photo-induced melting of charge and orbital order in the manganite Nd$_{0.5}$Sr$_{0.5}$MnO$_3$

The physics of perovskite manganites is a subject of intense research in condensed matter physics due to the interplay between charge, spin, lattice, and orbital degrees of freedom in these materials. The manganite Nd$_{0.5}$Sr$_{0.5}$MnO$_{3}$ is ferromagnetic below its Curie temperature ($T_{c})$ of $\sim $250 K, exhibiting colossal magnetoresistance upon application of a magnetic field. Below $T_{co}\sim $150 K, it is antiferromagnetic with charge and orbital ordering, which can be ``melted'' upon application of a high magnetic field. Optical conductivity measurements revealed an optical gap below $T_{co}$, with Drude-like behavior for $T_{co}