Fermi surface tuning in two-dimensional surface systems

Competing electronic interactions can be used to tune materials into different phases with interesting and sometimes exotic properties, ranging from magnetic long-range order to superconductivity. Such electronic interactions are particularly pronounced in low-dimensional systems, where electronic correlation is enhanced. On surfaces, the electronic states are easily accessible for manipulation by doping, adsorption or quantum confinement. A deliberate shift of the Fermi surface of 2D or 1D electron states can have a significant influence on chemical activity, adsorbate-adsorbate interactions, surface diffusion etc. More strikingly, it may drive phase transitions and can perhaps be used to realize Peierls-distorted, magnetically ordered and even superconducting phases in two dimensions. Using the Br/Pt(110) system as a case study, the possibility and the problems of a (quasi) continuous variation of a Peierls phase by Fermi surface tuning are examined.