Date(s) - 28/01/2009
3:20 pm - 4:20 pm
Title: Stripes and cuprates
Speaker: Dr. Young-June Kim, University of Toronto
Location: ABB 102
In certain high-temperature superconductors, neutron scattering experiments have revealed that doped holes and spins arrange themselves in orderly rows in the copper oxygen plane. In other cuprate materials, such stripes may also exist, although in most cases the stripes are not static but fluctuate with time and position. Understanding physics of stripes therefore may be very important in elucidating high temperature superconductivity. I will give a brief overview of charge and spin stripes in a number of cuprate compounds, studied with neutron and x-ray scattering. In particular, magnetic field and temperature dependence of charge stripes in La2-xBaxCuO4 (x ~ 1/8) will be discussed in detail. In our comprehensive x-ray scattering study, we found that the charge order in this sample is described with one-dimensional charge density waves, with simple sinusoidal structural modulation. Just below the structural transition temperature, short-range charge density wave correlation appears, which then develops into a large scale charge ordering below 40 K. However, the charge stripe correlation length exhibits unusual temperature and magnetic field dependence, suggesting that the charge stripe order competes with bulk superconductivity.