Crossover from non-Fermi liquid to Fermi liquid
behavior close to a quantum critical point
P. Schlottmann
Department of Physics, Florida State University,
Tallahassee, FL 32306, USA
January 15, 2008
Landau’s Fermi liquid theory has been successful in describing the low energy
properties of most normal metals. Numerous U, Ce and Yb based heavy fermion
systems display deviations from Fermi liquid behavior, known as non-Fermi
liquid behavior, which can be tuned by alloying (chemical pressure), hydrostatic
pressure or the magnetic field.
In most cases the systems are close to the
onset of antiferromagnetism and the non-Fermi liquid behavior is attributed to
a quantum critical point (QCP).
A nested Fermi surface together with the remaining interaction between the
carriers after the heavy particles are formed may give rise to itinerant antiferro-
magnetism. The model under consideration consists of an electron pocket and
a hole pocket, separated by a wave vector Q, and Fermi momenta kF1 and kF2,
respectively.1 The order can gradually be suppressed by increasing the mismatch
of the Fermi momenta, defined as δ = vF |kF1 − kF2|/2, and a quantum critical
point is obtained as TN → 0.
For critical mismatch of the Fermi vectors, δ0, (tuned QCP) the specific heat
over T increases as the logarithm of the temperature as T is lowered1,2 and the
linewidth of the quasi-particles is linear in T and ω.3 With increasing nesting
mismatch and decreasing temperature the specific heat and the linewidth display
a crossover from non-Fermi liquid (∼ T ) to Fermi liquid (∼ T 2) behavior.3 The
quasi-particle linewidth is a quantity relevant to the electrical resistivity, the
width of the inelastic neutron scattering quasi-elastic peak and the amplitude
of de Haas-van Alphen oscillations.
Work supported by the U.S. Department of Energy under grant DE-FG02-
98ER45707.
1 P. Schlottmann, Phys. Rev. B 59, 12379 (1999).
2 P. Schlottmann, Phys. Rev. B 68, 125105 (2003).
3 P. Schlottmann, Phys. Rev. B 73, 085110 (2006).
Keywords: heavy fermions, non-Fermi liquid, quantum critical point.
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