Abstract
AbstractThe thermal Hall effect has emerged as a potential probe of exotic excitations in spin liquids. In the Kitaev magnet $${{\alpha }}$$
α
-RuCl3, the thermal Hall conductivity $${{{\kappa }}}_{{{xy}}}$$
κ
x
y
has been attributed to Majorana fermions, chiral magnons, or phonons. Theoretically, the former two types of heat carriers can generate a “planar” $${{{\kappa }}}_{{{xy}}}$$
κ
x
y
, whereby the magnetic field is parallel to the heat current, but it is unknown whether phonons also could. Here we show that a planar $${{{\kappa }}}_{{{xy}}}$$
κ
x
y
is present in another Kitaev candidate material, Na2Co2TeO6. Based on the striking similarity between $${{{\kappa }}}_{{{xy}}}$$
κ
x
y
and the phonon-dominated thermal conductivity $${{{\kappa }}}_{{{xx}}}$$
κ
x
x
, we attribute the effect to phonons. We observe a large difference in $${{{\kappa }}}_{{{xy}}}$$
κ
x
y
between different configurations of heat current and magnetic field, which reveals that the direction of heat current matters in determining the planar $${{{\kappa }}}_{{{xy}}}$$
κ
x
y
. Our observation calls for a re-evaluation of the planar $${{{\kappa }}}_{{{xy}}}$$
κ
x
y
observed in$$\,{{\alpha }}$$
α
-RuCl3.
Funder
Canadian Institute for Advanced Research
Fonds de Recherche du Québec - Nature et Technologies
Canada Foundation for Innovation
Canada Research Chairs
Canada First Research Excellence Fund
Publisher
Springer Science and Business Media LLC
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