Anisotropic Thermal Conductivity Oscillations in Relation to the Putative Kitaev Spin Liquid Phase of α-RuCl3

In the presence of an external magnetic field, the Kitaev model could host either gapped topological anyons or gapless Majorana fermions. In α-RuCl3, the gapped and gapless cases are only separated by a 30° rotation of the in-plane magnetic field vector. The presence or absence of the spectral gap is key for understanding the thermal transport behavior in α-RuCl3. Here, we study the anisotropy of the oscillatory features of thermal conductivity in α-RuCl3. We examine the oscillatory features of thermal conductivities (κ//a, κ//b) with fixed external fields and find distinct behavior for the gapped (B//a) and gapless (B//b) scenarios. Furthermore, we track the evolution of thermal resistivity (λa) and its oscillatory features with the rotation of in-plane magnetic fields from B//b to B//a. The thermal resistivity λ(B,φ) displays distinct rotational symmetries before and after the emergence of the field-induced Kitaev spin liquid phase. These results suggest that oscillatory features of thermal conductivity in α-RuCl3 are closely linked to the putative Kitaev spin liquid phase and its excitations.