  Kitaev spin liquids (KSLs) contain both itinerant Majorana fermions and
localized $Z_2$ flux excitations. The mobile fermions transport energy, while
the fluxes hinder heat flow. By controlling the flux configuration, one can
separate a KSL into different domains via $Z_2$ flux walls. We show that at low
temperatures, the wall significantly suppresses the Majorana-mediated
Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction and blocks the heat transfer
between domains.
