Surface Magnetisation and Surface Correlations in Aperiodic Ising Models
  We consider the surface critical behaviour of diagonally layered Ising models on the square lattice where the inter-layer couplings follow some aperiodic sequence. The surface magnetisation is analytically evaluated from a simple formula derived by the diagonal transfer matrix method, while the surface spin-spin correlations are obtained numerically by a recursion method, based on the star-triangle transformation. The surface critical behaviour of different aperiodic Ising models are found in accordance with the corresponding relevance-irrelevance criterion. For marginal sequences the critical exponents are continuously varying with the strength of aperiodicity and generally the systems follow anisotropic scaling at the critical point. 
Ferenc Igloi and Peter Lajko