University of Wisconsin, Madison

Title: 2D fermions near an antiferromagnetic instability: non Fermi liquid behavior and pairing

Abstract: In this talk, I will consider the properties of 2D fermions near the boundary of the antiferromagnetic phase. This problem is relevant to both cuprates and heavy fermion materials. I focus on the situation when spin decay is allowed, i.e., at a mean-field level, the magnetic transition has a dynamical exponent z=2. For this problem, the RG consideration yields a marginal behavior at criticality. I show, however, that the actual situation is more complex due to the presence of anomalies, hidden from RG treatment. I argue that (i) the fermionic behavior is not marginal, and is more a non-Fermi liquid one, than one would expect from the RG study, (ii) the dynamic exponent z is different from 2, and (iii) as a peculiar consequence of a non-Fermi liquid behavior, the system at criticality is unstable towards a non-BCS pairing. I discuss the meaning of these results for cuprates.