Physical Review Letters
Transfer-Matrix Spectrum for Systems with Interfaces
Vladimir Privman A, Nenad M. Svrakic
Abstract
We consider Ising-type systems in the finite cross-section cylindrical geometry, with an interface imposed by the antiperiodic or + - boundary conditions. Closed forms are derived for the largest, asymptotically degenerate transfer-matrix eigenvalues. For rough interfaces ($0<T<{T}_{c}$ in 2D, ${T}_{R}<T<{T}_{c}$ in 3D), the eigenvalues are split algebraically, and the spectral gaps are governed by the surface stiffness coefficient. For "rigid" interfaces ($0<T<{T}_{R}$ in 3D), the splitting is exponential, and determined by the step-free energy.