Comment on "Transition from Bose glass to a condensate of triplons in Tl$_{1-x}$K$_x$CuCl$_3$"

TL;DR

This paper critically examines prior interpretations of calorimetric data in disordered quantum antiferromagnets Tl$_{1-x}$K$_x$CuCl$_3$, questioning the evidence for a Bose Glass phase and a true phase transition.

Contribution

It challenges previous claims of a Bose Glass phase and a field-induced phase transition in Tl$_{1-x}$K$_x$CuCl$_3$, providing a reanalysis that questions their validity.

Findings

No difference in crossover critical index between disordered and disorder-free samples

Questions the existence of a field-induced thermodynamic phase transition

Argues that prior interpretations of data are not unambiguous

Abstract

We argue that the interpretation of the calorimetric data for disordered quantum antiferromagnets Tl$_{1-x}$K$_x$CuCl$_3$ in terms of Bose Glass physics by F. Yamada {\it et al.} in [Phys. Rev. B {\bf 83}, 020409(R) (2011)] is not unambiguous. A consistent analysis shows no difference in the crossover critical index for the disorder-free TlCuCl$_3$ and its disordered derivatives. Furthermore, we question the very existence of a proper field-induced thermodynamic phase transition in Tl$_{1-x}$K$_x$CuCl$_3$.