Figure 5 FTIR spectra of the as-grown and postannealed samples. The peak at 2,360.39 cm-1 is due to contributions from CO2 present in air. Finally, we are interested in the magnetic properties of these films. The in-plane hysteresis loops for the as-grown films shown in Figure 6a were measured by SQUID with the magnetic field (H) parallel to the EuTiO3 direction at 300 K. The as-grown EuTiO3 films exhibit a ferromagnetic-like behavior. To quantitatively show
the impact of the postannealing on its magnetic properties, the same piece of the sample after annealing was measured by SQUID to avoid errors from sample volume measurements. A striking decrease of M S and a negligible ferromagnetic behavior for the annealed films are found and shown in Figure 6a. These results indicate that the oxidation states of Eu in the Selleck AR-13324 as-grown films provides magnetic moments and contributes to the magnetization. In order to get more information about the magnetism in these films, the in-plane hysteresis loops for the as-grown and annealed films
were measured at 2 K. It can be seen from the loops shown in Figure eFT-508 ic50 6a that both films exhibit a ferromagnetic behavior and an increase of M S at 2 K. Surprisingly, the M S value of the annealed films is much larger than that of the as-grown films at 2 K. It means that Eu2+ in the annealed films has magnetic contribution to magnetization at low temperature and implies that Eu3+ ion probably possesses less magnetic moment than Eu2+. Temperature dependence of the magnetization curves shown in Figure 6b compares the magnetic properties between the as-grown and annealed films in more detail. It clearly shows that the annealed films convert to ferromagnetic behavior as external magnetic field applied to
the films is raised, implying the presence of a ferromagnetic phase transition in the annealed films at low temperature. Evidently, a thermal treatment of the as-grown films demonstrates obvious impact on their magnetic properties. Combining this result with that from XPS investigations, we can obtain that the BI 10773 order valence instabilities of Eu in EuTiO3 films could result in the material being Buspirone HCl ferromagnetic at room temperature, which may extend the range and potential of this material for application. Figure 6 Hysteresis loops and temperature dependence of magnetization. (a) Hysteresis loops obtained at 300 and 2 K for the as-grown and annealed films with external field applied parallel to EuTiO3 direction. The inset magnifies the low magnetic field range. (b) Temperature dependence of the magnetization curves of the as-grown and annealed films at 1,000 Oe and 20 kOe external fields applied parallel to EuTiO3 direction. Conclusions To summarize and conclude, using a hydrothermal method, EuTiO3 films with high crystalline quality were successfully grown on SrTiO3(001) substrate at a temperature of 150°C.