  The coupling between phonon and magnon is ubiquitous in magnetic materials
and plays a crucial role in many aspects of magnetic properties, most notably
in spintronics. Yet, this academically and technologically interesting problem
still poses a severe challenge to a general understanding of the issue in
certain materials. We report that Ni3TeO6 exhibits clear evidence of
significant magnon-phonon coupling in both longitudinal thermal conductivity
($\kappa_{xx}$) and thermal Hall coefficient ($\kappa_{xy}$). The
Debye-Callaway model, a phenomenological description for phonon heat
conduction, can explain the measured magnetic field dependence of
$\kappa_{xx}(H)$: phonon scattering from spin fluctuation in the paramagnetic
phase and additional scattering due to magnon-phonon coupling in the collinear
antiferromagnetic phase. We further suggest that a similar approach could be
applied to understand the finite $\kappa_{xy}$ values in $Ni_3TeO_6$.
