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 ω Δ0 near the Fermi level, where Δ0 is the ground-state spin splitting for magnetically ordered ground state, and Δ T1 2ln1 2(vF T) in the quantum critical regime (vF 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 Δ0 the vertex corrections become important and the Eliashberg approach is not justified. The results for the spectral properties and susceptibilities in the quantum critical regime near charge (spin) instabilities with large enough correlation length ξ (T vF)-1 3 are obtained.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 15 Jul 2005|