Evidence for a nematic phase in La$_{1.75}$Sr$_{0.25}$NiO$_{4}$
  Determining the nature of electronic states in doped Mott insulators remains a challenging task. In the case of tetragonal La$_{2-x}$Sr$_{x}$NiO$_{4}$, the occurrence of diagonal charge and spin stripe order in the ground state is now well established. In contrast, the nature of the high-temperature "disordered" state from which the stripe order develops has long been a subject of controversy, with considerable speculation regarding a polaronic liquid. Following on the recent detection of dynamic charge stripes, we use neutron scattering measurements on an $x=0.25$ crystal to demonstrate that the dispersion of the charge stripe excitations is anisotropic. This observation provides compelling evidence for the presence of electronic nematic order. 
Ruidan Zhong, Barry L. Winn, Genda Gu, Dmitry Reznik, J. M. Tranquada
cond-mat.str-el