Thermoelectric properties of single-phase full-Heusler alloy Fe2TiSi films with D3-type disordering

Fe2TiSi has been expected to be one of the high-performance thermoelectric full-Heusler alloys. Here, we experimentally clarify the room-temperature Seebeck coefficient (S) and thermal conductivity (κ) for the Fe2TiSi films. Using a molecular beam epitaxy technique, we demonstrate the high degree of L21-ordering and the homogeneous single-phase structure in the Fe2TiSi films. We find that the intrinsic conduction carriers of the Fe2TiSi films are holes and impurity-induced carrier scattering is indicated, derived from weak magnetic moments due to the presence of D03-type (Fe ⇔ Ti) structural disorder in the Fe2TiSi film. From reliable measurements for thin films, the values of S and κ are estimated to be 101 μV/K and 5.6 W/(m K), respectively, at room temperature. This study will open a new way for full-Heusler alloy thermoelectric materials other than those in Fe2VAl systems.