173 research outputs found
Universal behavior of Ferromagnet at Quantum Critical Point
The heavy-fermion metal can be tuned from ferromagnetism
at to non-magnetic state at some critical concentration . The
non-Fermi liquid behavior (NFL) at is recognized by power low
dependence of the specific heat given by the electronic contribution,
magnetic susceptibility and volume expansion coefficient
at low temperatures: . We
also demonstrate that the behavior of normalized effective mass
observed in at agrees with that of
observed in paramagnetic and conclude that these alloys
exhibit the universal NFL thermodynamic behavior at their quantum critical
points. We show that the NFL behavior of can be accounted
for within frameworks of quasiparticle picture and fermion condensation quantum
phase transition, while this alloy exhibits a universal thermodynamic NFL
behavior which is independent of the characteristic features of the given alloy
such as its lattice structure, magnetic ground state, dimension etc.Comment: 5 pages, 3 figure
Energy scales and the non-Fermi liquid behavior in YbRh2Si2
Multiple energy scales are detected in measurements of the thermodynamic and
transport properties in heavy fermion metals. We demonstrate that the
experimental data on the energy scales can be well described by the scaling
behavior of the effective mass at the fermion condensation quantum phase
transition, and show that the dependence of the effective mass on temperature
and applied magnetic fields gives rise to the non-Fermi liquid behavior. Our
analysis is placed in the context of recent salient experimental results. Our
calculations of the non-Fermi liquid behavior, of the scales and thermodynamic
and transport properties are in good agreement with the heat capacity,
magnetization, longitudinal magnetoresistance and magnetic entropy obtained in
remarkable measurements on the heavy fermion metal YbRh2Si2.Comment: 8 pages, 8 figure
Asymmetric tunneling, Andreev reflection and dynamic conductance spectra in strongly correlated metals
Landau Fermi liquid theory predicts that the differential conductivity
between metallic point and metal is a symmetric function of voltage bias V.
This symmetry holds if the particle-hole symmetry is preserved. We show that
the situation can be different when one of the two metals is a strongly
correlated one whose electronic system can be represented by a heavy fermion
liquid. When the heavy fermion liquid undergoes fermion condensation quantum
phase transition, the particle-hole symmetry is violated making both the
differential tunneling conductivity and dynamic conductance asymmetric as a
function of applied voltage. This asymmetry can be observed when the strongly
correlated metal is either normal or superconducting. We show that at small
values of $V the asymmetric part of the dynamic conductance is a linear
function of V and inversely proportional to the maximum value of the gap and
does not depend on temperature provided that metal is superconducting, when it
becomes normal the asymmetric part diminishes at elevated temperatures.Comment: 8 pages, 7 figure
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