Magnetically Robust Non-Fermi Liquid Behavior in Heavy Fermion Systems with f^2-Configuration: Competition between Crystalline-Electric-Field and Kondo-Yosida Singlets

TL;DR

This paper investigates how magnetic fields influence non-Fermi liquid behavior in heavy fermion systems with f^2 configuration, revealing conditions under which NFL behavior remains robust near quantum critical points.

Contribution

It demonstrates that NFL behavior near QCP can be stable against magnetic fields due to competition between crystalline-electric-field and Kondo-Yosida singlets, using numerical renormalization methods.

Findings

The characteristic temperature T_F^* is unaffected by magnetic fields up to H_z^*.

NFL behavior remains robust against magnetic fields near QCP within certain parameter regions.

Robust NFL behavior persists at observable temperatures T > T_F^* up to H_z^*, which exceeds T_F^*.

Abstract

We study a magnetic field effect on the Non-Fermi Liquid (NFL) which arises around the quantum critical point (QCP) due to the competition between the f^2-crystalline-electric-field singlet and the Kondo-Yosida singlet states by using the numerical renormalization ground method. We show the characteristic temperature T_F^*, corresponding to a peak of a specific heat, is not affected by the magnetic field up to H_z^* which is determined by the distance from the QCP or characteristic energy scales of each singlet states. As a result, in the vicinity of QCP, there are parameter regions where the NFL is robust against the magnetic field, at an observable temperature range T > T_F^*, up to H_z^* which is far larger than T_F^* and less than min(T_{K2}, $Delta).