Scaling behavior and giant field-enhancement of the thermal conductivity in the honeycomb antiferromagnet BaCo2(AsO4)2

Abstract

The layered honeycomb material BaCo${}_2$(AsO${}_4$)${}_2$ (BCAO) is of topical interest because its magnetic state is related to that of the Kitaev magnet $\alpha$-RuCl${}_3$. Using thermal transport to probe how magnetic excitations interact with phonons in the magnetically disordered regime, we have uncovered an unusually large enhancement of the thermal conductivity ${\kappa }_{xx}$ in an in-plane magnetic field $\mathbf{H}$. Just above the Néel temperature $T_{\mathrm{N}}$, a field of 13 T increases ${\kappa }_{xx}$ by a factor $\sim 211$, much larger than reported previously in any magnetic insulator. Interestingly, ${\kappa }_{xx}(H,T)$ exhibits a scaling behavior in the entire magnetically disordered region that surrounds the ordered zigzag state. The ratio $\Delta {\kappa }_{xx}(H,T)/{\kappa }_{xx}(13,T)$, measured throughout the disordered region, collapses to a one-parameter scaling function $\exp (-1/gx)$ (where $x={\mu }_{\mathrm{B}}B/k_{\mathrm{B}}T$ and $g$ is a constant).

8 pages, 4 figures

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Cited by in corpus (1)

• BaCo${}_2$(AsO${}_4$)${}_2$: Strong Kitaev, After All