Electronic self-energy and triplet pairing fluctuations in the vicinity of a ferromagnetic instability in two-dimensional systems: Quasistatic approach

The self-energy, spectral functions, and susceptibilities of two-dimensional systems with strong ferromagnetic fluctuations are considered within the quasistatic approach. The self-energy at low temperatures T has a non-Fermi-liquid form in the energy window vertical bar omega vertical bar less than or similar to Delta(0) near the Fermi level, where Delta(0) is the ground-state spin splitting for magnetically ordered ground state, and Delta(0)proportional to T-1/2 ln(1/2)(v(F)/T) in the quantum critical regime (v(F) is the Fermi velocity). Spectral functions have a two-peak structure at finite T above the magnetically ordered ground state, which implies quasisplitting of the Fermi surface in the paramagnetic phase in the presence of strong ferromagnetic fluctuations. The triplet pairing amplitude in the quasistatic approximation increases with increasing correlation length; at low temperatures T (T/v(F))(-1/3) are obtained.