Out-of-equilibrium properties of the semi-infinite kinetic spherical model

We study the ageing properties of the semi-infinite kinetic spherical model at the critical point and in the ordered low-temperature phase for both Dirichlet and Neumann boundary conditions. The surface fluctuation–dissipation ratio and the scaling functions of two-time surface correlation and response functions are determined explicitly in the dynamical scaling regime. In the low-temperature phase, our results show that for the case of Dirichlet boundary conditions the value of the non-equilibrium surface exponent b 1 differs from the usual bulk value of systems undergoing phase ordering.