Laser-induced off-diagonal thermoelectric voltage in La 1− xCa xMnO 3 thin films

Abstract

Laser induced off-diagonal thermoelectric voltages were observed in La 0.67Ca 0.33MnO 3 thin films deposited on vicinal cut SrTiO 3 substrates, as well as in films of other doping levels. The dependence of this voltage on photon fluence, illuminated length of the film, film thickness and orientation are in remarkable analogy to the results reported for YBa 2Cu 3O 7− x thin films. That suggests an identical physical mechanism in both materials which based on the existence of off-diagonal elements in the Seebeck tensors. It demonstrates that an intrinsically anisotropic charge transport exists in these series of materials, in spite of the quasi-cubic crystal structure of the base material LaMnO 3. From the results obtained on films with a systematic variation of the doping level and materials, the anisotropy of the Seebeck tensor is suggested to be a contribution of the long-range cooperative Jahn–Teller distortions.