Magnetic fluctuations at high energies in parent La2CuO4

The LCO is a quasi-2D anti-ferromagnetic insulator which can be doped into a superconductor. Seemingly simple, its 2D magnetic behaviors have recently displayed some new features, which were published in a PRL days ago [PRL 105, 247001 (2010)]. They used INS as the probes. They found some unusual traits with the zone corner fluctuations with momenta around (pi,0). The dispersion around this point is much broader and with long tail in comparison with, let's say, the (pi/2, pi/2) region. Moreover, significant spectral weight were disclosed over there. The authors proposed spinon as the cause of the broad peak: a magnon decays into spinons mostly at zone corners. The decay shortens its life time and increases the peak width.