The report of a half-quantized thermal Hall effect and oscillatory structures in the magnetothermal conductivity in the Kitaev material α-RuCl₃ have sparked a strong debate on whether it is generated by Majorana fermion edge currents, spinon Fermi surface, or whether other more conventional mechanisms are at its origin. Here, we report low temperature thermal conductivity (κ) of another candidate Kitaev material, Na₂Co₂TeO₆. The application of a magnetic field (B) along different principal axes of the crystal reveals a strong directional-dependent B impact on κ, while no evidence for mobile quasiparticles except phonons can be concluded at any field. Instead, severely scattered phonon transport prevails across the B−T phase diagram, revealing cascades of phase transitions for all B directions. Our results thus cast doubt on recent proposals for significant itinerant magnetic excitations in Na₂Co₂TeO₆, and emphasize the importance of discriminating true spin liquid transport properties from scattered phonons in candidate materials.

关于Kitaev材料α -RuCl ₃中磁热导率的半量子化热霍尔效应和振荡结构的报道引发了激烈的争论：它是由马约拉纳费米子边缘电流、自旋费米面还是其他更传​​统的产生的机制是其根源。在这里，我们报告了另一种候选 Kitaev 材料 Na ₂ Co ₂ TeO ₆的低温导热率 ( κ ) 。沿晶体不同主轴施加磁场 ( B ) 揭示了B对κ 的强烈方向依赖性影响，而在任何场都无法得出除声子之外的移动准粒子的证据。相反，B - T相图中普遍存在严重分散的声子输运，揭示了所有B方向的级联相变。因此，我们的结果对最近关于 Na ₂ Co ₂ TeO ₆中显着巡回磁激发的提议提出了质疑，并强调了区分真实自旋液体传输特性与候选材料中散射声子的重要性。