DCMPMS Seminars

Stripes in high-Tc superconductors as detected by resonant soft X-ray scattering

by Prof. Jörg Fink (Helmholtz-Zentrum Berlin & Leibniz-Institute for Solid State and Materials Research Dresden)

Thursday, November 19, 2009 from to (Asia/Kolkata)
at Colaba Campus ( AG-66 )
In the doped cuprates there exists a complex interplay between lattice, charge and spin degrees of freedom yielding several phases in a narrow concentration range: the antiferromagnetic insulating phase, the high-Tc superconducting phase, the pseudo-gap region and charge- and spin-ordered phases. The latter are usually divided into checkerboard phases and stripe phases. In the stripe phases antiferromagnetic antiphase magnetic domains are separated by periodically spaced domain walls to which the holes segregate. We used resonant soft X-ray scattering with photon energies near the O K and the Cu L3 edges to study the charge ordering in the systems La2−xBaxCuO4   and La1.8−xEu0.2SrxCuO4. This method is the only one in which static charge ordering can be directly detected. A complete phase diagram could be derived  for the charge ordering which will be compared with structural and spin ordering. The influence of stripe ordering on the mechanism of high-Tc superconductivity will be discussed.
Organised by Margaret D'Souza