Non-Fermi-Liquid Behavior in Itinerant Antiferromagnets

016405-1 We consider a two-dimensional itinerant antiferromagnet near a quantum-critical point. We show that, contrary to conventional wisdom, fermionic excitations in the ordered state are not the usual Fermi-liquid quasiparticles. Instead, down to very low frequencies, the fermionic self-energy varies as !2=3. This non-Fermi-liquid behavior originates in the coupling of fermions to the longitudinal spin susceptibility k q; in which the order-induced ‘‘gap’’ in the spectrum at q 0 dissolves into the Landau damping term at vFq > . The transverse spin fluctuations obey the z 1 scaling characteristic of spin waves, but remain overdamped in a finite range near the critical point.