A rotor for a gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, a rotor disk rotatable about an axis and a gas path wall coupled to and radially outward of the rotor disk. The gas path wall bounds a radially inward portion of a gas path. A plurality of rotor spokes are radially intermediate the rotor disk and the gas path wall. The plurality of rotor spokes is circumferentially spaced to define a plurality of cooling channels intermediate the rotor disk and the gas path wall. A thermal barrier coating is disposed on a surface of at least one of the plurality of cooling channels. A method of cooling a rotor assembly is also disclosed.