Fermi-surface engineering of a devil's staircase

In quasi-one-dimensional electronic systems a strong electron-phonon coupling is expected. This may stabilize a charge-density-wave ground state, where both, the charge and the geometry of the system are modulated with periodicity q=2k(F). We use an adparticle-induced shift of the Fermi wave vector k(F) in such a system to continuously tune the overlayer geometry. Three different commensurate structures are observed, which are separated by fluid and chaotic soliton phases. The phase diagram can be viewed as forming the so-called "devil's staircase".