Critical fluctuations and quenched disordered two-dimensional charge stripes in La5/3Sr1/3NiO4

Using high-resolution x-ray scattering, we have demonstrated the existence of quenched disordered charge stripes in a single crystal of La5/3Sr1/3NiO4 at low temperatures. Above the second-order transition critical scattering was observed due to fluctuations into the charge stripe phase. The charge stripes are shown to be two dimensional in nature both by measurements of t heir correlation lengths (xi(a) approximate to 185 Angstrom, xi(b) = 400 An gstrom, and xi(c) approximate to 25 Angstrom) and by the critical exponents of the charge strip transition. The charge stripe orderings did not develo p long-range order even at low temperatures, indicating that the charge str ipes are disordered and that the length scale of the disorder is quenched.