Drastic annealing effects in transport properties of single crystals of the YbNi2B2C heavy fermion system

TL;DR

This study investigates how annealing affects the transport properties of YbNi2B2C heavy fermion crystals, revealing significant changes in resistivity and thermoelectric power due to local Kondo temperature redistributions, while thermodynamic properties remain stable.

Contribution

It demonstrates that annealing alters transport properties through local Kondo temperature redistribution without affecting thermodynamic behavior.

Findings

Resistivity and thermoelectric power vary significantly with annealing.

Thermodynamic properties remain unchanged after annealing.

Local Kondo temperature redistribution explains transport property changes.

Abstract

We report temperature dependent resistivity, specific heat, magnetic susceptibility and thermoelectric power measurements made on the heavy fermion system YbNi2B2C, for both as grown and annealed single crystals. Our results demonstrate a significant variation in the temperature dependent electrical resistivity and thermoelectric power between as grown crystals and crystals that have undergone optimal (150 hour, 950 C) annealing, whereas the thermodynamic properties: (c_p(T) and chi(T)) remain almost unchanged. We interpret these results in terms of redistributions of local Kondo temperatures associated with ligandal disorder for a small (~ 1%) fraction of the Yb sites.