Simple model for non-Fermi-liquid behavior induced by antiferromagnetic spin fluctuations
- Department of Physics, Florida State University, Tallahassee, Florida 32306 (United States)
We consider a simple model for itinerant antiferromagnetism consisting of an electron pocket and a hole pocket separated by a wave vector {bold Q}. The nesting of the Fermi surfaces leads to a spin-density wave instability for repulsive Hubbard coupling and to charge-density waves for an attractive interaction. The order can gradually be suppressed by mismatching the nesting and a quantum critical point is obtained as T{sub N}{r_arrow}0. In the disordered phase perturbative corrections are logarithmic in the external frequency or the temperature. We investigate the renormalization-group flow of the model in leading and next-to-leading logarithmic order. The linear-response correlation functions for spin-density and charge-density waves are calculated. The specific-heat {gamma} coefficient and the uniform magnetic-field susceptibility increase on a logarithmic scale when the temperature is lowered. The Wilson ratio is temperature dependent and nonuniversal. The Fermi-liquid picture breaks down at the ordering temperature T{sub N} or at a quantum critical point. Our results are valid in the disordered phase for weak and intermediate coupling, but not in the critical region. The results are discussed in the context of non-Fermi-liquid behavior found in some heavy fermion compounds (the two pockets are then part of the Fermi surface of the heavy electron bands). {copyright} {ital 1999} {ital The American Physical Society}
- OSTI ID:
- 338707
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 19 Vol. 59; ISSN 0163-1829; ISSN PRBMDO
- Country of Publication:
- United States
- Language:
- English
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