Determination of Thermal Diffusivity of a Manganite Thin Film

Thermal diffusivity has been investigated in a manganite thin film La_0.6Sr_0.4MnO₃ by means of transient grating (TG) technique at room temperature. A new method, which is generalized to two-layered samples of the thin film deposited on a semi-infinite substrate, is established to fit the TG signals. The thermal diffusivity of the La_0.6Sr_0.4MnO₃ thin film with a thickness of 200nm on an MgO (100) substrate is determined to be 0.92mm²/s, which is slightly smaller than that of the single crystal sample (1mm²/s).