Fermiological interpretation for collective spin and charge orderings in underdoped La-based cuprates by ARPES

By using ARPES interpretation for the origin of the collective spin and charge orderings in underdoped La-based cuprate superconductors is carefully examined. A Fermi surface nesting wave vector is identified which closely matches the collective ordering wave vector observed by neutron scattering for doping around 1/8. The pseudogap state is found to be essential for the development of such nesting instability of the electronic system toward density wave formation. A systematic doping dependence study will be presented that allows further insights into this issue.