Doping dependence of laser-induced transverse thermoelectric voltages in the perovskite Nd2−x Ce x CuO4 thin films

Abstract

Large laser-induced thermoelectric voltages (LITVs) are measured in the electron-doped Nd 2-x Ce xCuO 4 thin films grown on the vicinal-cut SrTiO 3 substrates by pulsed laser deposition. The dependence of LITV signals upon the doping carrier density is investigated by changing the Ce content of the films. The optimum Ce dopant corresponding to the largest voltage is found and is attributed to the two-dimensional transport behaviors of the localized electrons. The shorter laser irradiation always induces the larger voltage signals in samples with richer Ce content, suggesting the optimum dopant level is sensitive to the wavelength of excitation source. Thus, the behaviors of LITV signals are resulted from both effects of the anisotropic thermoelectric transport and the optical properties of the thin films. The doping dependence related with an anisotropic charge transport may come from the change in carrier density and the modification in energy band configuration.

Metabolic profiling of petroleum-degrading microbial communities incubated under high-pressure conditions

“…In a recent study, Firmicutes, Thermotogae, Deltaproteobacteria, and Synergistetes were observed under sulfate-reducing and high-temperature conditions (Xiong et al, 2015). Accordingly, Firmicutes and Thermotogae were found to be abundant in our sulfate-reducing community, as well as in our methanogenic community.…”

Enhanced Bidimensionality‐Driven Ultrahigh Laser‐Induced Voltages in High‐Tc Superconducting Epitaxial Films

“…As expected, A ‐site Ba/Nd substitution can greatly expand the lattice in c ‐axis, giving rise to the decoupling of 2D CuO 2 planes, which drastically increases the structural bidimensionality in terms of, e.g., charge transport and thermoelectric effect, etc. Strikingly, ultrahigh LIVs of larger than 50 V was therefore achieved for the first time, orders higher than that of isostructural superconducting cuprate and three folds larger than that of reported largest values to date …”

“…Subject to long‐term endeavors, the involved origin of LIVs seems clearly stemming from the off‐diagonal term of the Seebeck tensor which is intrinsically associated with the anisotropy in structures, transport, and thermoelectric power, but in fact was determined or mainly achieved by the artificial film orientations . Abundant experimental methods and strategies or newly material system explorations, aiming at improving LIVs, therefore have been performed base on these points . For instance, A ‐site substitution with Ag in La 0.6 Pb 0.4 MnO 3 manganite, due to increasing the amount of Mn 4+ , could greatly enhanced electrical and magnetic transport properties which eventually favor anisotropic Seebeck enhancement .…”

“…[4,6,19] The anisotropy in thermoelectric power that dominates the LIV behaviors in such family sorts has been steadily identified, which thus seems good candidates for high LIVs, but many attempts failed to reach exquisite structural tailoring. [14][15][16][17][18] The open issue thus becomes high electronic transport can be maintained simultaneously but to what extent the structural anisotropy can be tuned.…”