Instabilities at [110] surfaces of dx2-y2 superconductors

We compare different possible origins for the low-temperature splitting of the zero-energy peak in the local density of states at (110) surfaces of dx2-y2-wave superconductors. Using a tight-binding model with interactions in the Bogolyubov-de Gennes treatment, we discuss the instability of the superconductor against a current-carrying locally time-reversal symmetry-breaking phase (s + id-wave) and, alternatively, a spin density wave-like state. The former (latter) is more likely to occur in a regime corresponding to the overdoped (underdoped) situation of high-temperture superconductors. (orig.)