Resolution of Entropy $\ln \sqrt 2$ by Ordering in Two-Channel Kondo Lattice

TL;DR

This paper clarifies the electronic ordering in the two-channel Kondo lattice, revealing a transition associated with a specific entropy change and the formation of heavy electron bands below the transition temperature.

Contribution

It introduces a novel composite order parameter involving local and itinerant electrons, explaining entropy change and the formation of heavy fermions in the two-channel Kondo lattice.

Findings

Entropy change close to ln(√2) per site during transition

Heavy electron band forms rapidly below the transition temperature

Order involves instability of Majorana particles towards heavy fermions

Abstract

Peculiar property of electronic order is clarified for the two-channel Kondo lattice. With two conduction electrons per site, the order parameter is a composite quantity involving both local and itinerant degrees of freedom. In contrast to the ordinary Kondo lattice, a heavy electron band is absent above the transition temperature, but is rapidly formed below it. The change of entropy associated with the ordering is found to be close to $\ln \sqrt 2$ per site. This entropy corresponds to the residual entropy in a two-channel Kondo impurity, which has been regarded as due to localized free Majorana particles. The present composite order is interpreted as instability of Majorana particles toward non-Kramers conduction electrons plus heavy fermions that involve localized electrons.