Specific Heat Study of Non-Fermi Liquid Behavior in CeNi_2Ge_2: Anomalous Peak in Quasi-Particle Density-of-States

TL;DR

This study investigates non-Fermi liquid behavior in CeNi_2Ge_2 through specific heat measurements, revealing an anomalous peak in the quasi-particle density-of-states at the Fermi energy that explains the observed thermodynamic properties.

Contribution

The paper introduces a model with an anomalous peak in the quasi-particle density-of-states to explain NFL behavior in CeNi_2Ge_2, supported by specific heat and magnetocaloric effect data.

Findings

C/T exhibits a T^{1/2} dependence destroyed by magnetic field.

An anomalous peak in the DOS at the Fermi energy explains the data.

Absence of residual entropy at T=0 K confirmed by magnetocaloric measurements.

Abstract

To investigate the non-Fermi liquid (NFL) behavior in a nonalloyed system CeNi_2Ge_2, we have measured the temperature and field dependences of the specific heat C on a CeNi_2Ge_2 single crystal. The distinctive temperature dependence of C/T (~a-b*T^(1/2)) is destroyed in almost the same manner for both field directions of B//c-axis and B//a-axis. The overall behavior of C(T,B) and the low-temperature upturn in magnetic susceptibility can be reproduced, assuming an anomalous peak of the quasi-particle-band density-of-states (DOS) at the Fermi energy possessing (epsilon)^(1/2) energy dependence. Absence of residual entropy around T=0 K in B~0 T has been confirmed by the magnetocaloric effect measurements, which are consistent with the present model. The present model can also be applied to the NFL behavior in CeCu_{5.9}Au_{0.1} using a ln(epsilon)-dependent peak in the DOS. Possible origins of the peak in the DOS are discussed.