Thermal Transport of Co-based Kitaev Material BaCo2(AsO4)2*

The Kitaev Quantum Spin Liquid (KQSL) has attracted much attention because the Kitaev Hamiltonian can be solved exactly and its excitations are Majorana fermions and vortices. Previous work has mostly focused on 4d and 5d transition metal based materials, such as a-RuCl3. Here we present measurements on a Co-based honeycomb material BaCo2(AsO4)2, which exhibits different interaction energy scales that may lead to a more ideal Kitaev material. For example, it has a lower critical field for suppressing antiferromagnetism than that in RuCl3. This enables easier access to the candidate field-induced spin liquid state. We have explored its rich temperature-field phase diagram via thermal transport measurements. Our results reveal remarkable sensitivity of the thermal conductivity to the underlying magnetic phases and transitions between them. In particular, we present magnetic hysteresis and thermal hall data that provide new information about the underlying states and Kitaev physics more broadly.

Supported by NSF DMR-2011750 and DOE (DE-SC0017863 and DE-SC0019331)