SPIN DENSITY WAVE ORDER IN THE SUPERCONDUCTING STATE OF La_(2)CuO_(4+Y)

摘要

In the high temperature (high-T_(c)) superconductors, the multiple roles played by the electrons continue to defy theoretical understanding. It appears that all high-T_(c) superconductors are based on structures with CuO_(2) planes, in which the electrons on neighboring copper ions are strongly coupled magnetically. In systems based on La_(2)CuO_(4), antiferromagnetism is a dominant feature of the phase diagram at low doping levels, and conventional itinerant-electron behavior dominates in the high doping regime. Intermediate doping levels are described by neither, but this is where the superconducting properties are optimal. In our experiments, we focus on the evolution of magnetic properties from the insulating antiferromagnet to the superconductor.