Electronic topological transition in 2D electron system on a square lattice as a motor for the 'strange-metal' behaviour in high-T-c cuprates

We show that a 2D system of free electrons on a square lattice with hoping between more than nearest neighbours is characterised by two quantum critic al points associated with a change in topology of Fermi surface as a functi on of electron concentration. This simple model (when taking into account a positive interaction in a triplet channel) allows us to consistently expla in some crucial experiments in the underdoped regime of hole-doped high T-c cuprates (ARPES, neutron scattering). (C) 1998 Elsevier Science Ltd. All r ights reserved.